feat(forge): Phases 2+2.1+3 — Gitea + GitLab providers, per-call routing, local-merge fallback (#575)

* feat(forge): Phase 2 — Gitea provider, per-call routing, host registry

Gitea support lands behind the Phase-1 seam:

- GiteaProvider (services/forge/gitea.py): Gitea v1 transport addressed
  by instance host (api base from the project's git_url). Where Gitea's
  wire contract diverges from GitHub's, the provider adapts responses
  back into the shapes GitService already classifies (ShapedResponse):
  `token` auth scheme, duplicate-PR 409→422 with the "already exists"
  text GitService keys on, commit statuses reshaped into check_runs /
  workflow_runs envelopes, APPROVE→APPROVED review mapping, Do-keyed
  POST merge, merge-method repo keys, label-color '#' prefix,
  client-side head/base PR filtering. Deliberate postures per the spec:
  zero-workflows fail-open (statuses-free repo → no_ci_configured) and
  merge_branch as a shaped 501 (env-sync cascade lands on missing_ref;
  the shared local-git fallback is Phase-2.1).
- ForgeRouter (services/forge/router.py): GitService._forge now routes
  per call from RepoRef.host — every existing call site unchanged in
  shape. RepoRef gains an optional host; _parse_git_url returns the
  host-stamped ref and it is threaded through GitService/release
  executor instead of being rebuilt from strings (helpers re-signatured
  to take RepoRef).
- Host registry (services/forge/registry.py): in-memory host→provider
  map, self-healing — ProjectService.get/get_by_slug re-register on
  every read; provider_for resolves gitea projects by git_url host.
- Registration validation now accepts git_provider="gitea"; GitLab
  remains recognized-but-rejected. Panel: the read-only Forge badge
  becomes a real picker (Auto-detect / GitHub-GHE / Gitea / GitLab
  disabled).

Plain git (clone/fetch/push) needs no changes — the Basic-auth
extraheader works on Gitea unchanged. Gates: mypy 392 files, xenon A,
full unit suite 6356 green, integration suite 2257 green.

* feat(forge): live-Gitea contract suite + scheme support + slash-safe refs

Hardening from running the provider against a real dockerized Gitea
1.22.6 (the spec's Phase-2 contract suite, now committed as the
env-gated tests/e2e_smoke/test_gitea_live.py — self-seeding: creates its
own repo, pushes real commits, and drives PR open → duplicate reshape →
list/filter → diff → review → labels → commit-status CI reshapes →
squash merge → branch delete → release, plus a live verification of the
x-access-token Basic-auth git-CLI claim).

Two real findings fixed:
- Branch refs weren't URL-encoded — every RoboCo branch carries slashes
  (feature/backend/...), and Gitea's router 404s on the extra path
  segments. list_ci_runs + delete_branch_ref now quote the ref
  (regression-pinned in the unit suite).
- The API base hardcoded https; a LAN instance serving plain http is a
  real deployment shape. GiteaProvider gains a scheme (recorded per host
  by the registry from the project's git_url).

ShapedResponse moves to forge/shaping.py (shared by the upcoming GitLab
transport, which needs its text override for diff reassembly).

* feat(forge): Phase 3 GitLab provider + Phase 2.1 local-merge fallback

GitLabProvider (services/forge/gitlab.py): GitLab v4 transport addressed
by host+scheme, subgroup-safe (the MR project path packs into
RepoRef.owner, URL-encoded per call). Adapters translate MR semantics
into the GitHub shapes GitService classifies: iid→number,
source/target_branch→head/base with a merged bool, per-file diffs
reassembled into unified-diff text (ShapedResponse text override,
3-page cap), approve-vs-note review routing (GitLab has no
request-changes verb), pipelines/statuses reshaped into
workflow_runs/check_runs, merge-method repo-key mapping, duplicate-MR
409→422. Reviewer mirroring is skipped (needs numeric ids RoboCo
doesn't store); provisioning stays Phase 4. gitlab.com now auto-detects
at registration like github.com; self-hosted GitLab sets the provider
explicitly (panel picker enabled).

Phase 2.1: neither Gitea nor GitLab has GitHub's server-side merges
API — their merge_branch returns a shaped 501 and
GitService.sync_env_branch now runs the shared local-git fallback
(_local_merge_branch: throwaway clone → ancestor check → merge → push;
a conflict aborts with the remote untouched; same status vocabulary as
the merges-API path).

Also aligns the whole tree with the full gate's tests/-scoped mypy
(provider-test responder typing, e2e_smoke's stale owner/repo shapes).
Gates: mypy 1229 files clean, xenon A, unit suite 6393 green, forge
suites 85 green, panel typecheck/lint clean.

---------

Co-authored-by: Renn F <rennf93@users.noreply.github.com>

tests/unit/services/test_git_merge_method_fallback.py

@@ -15,6 +15,7 @@ from unittest.mock import AsyncMock, MagicMock
 import pytest
 import roboco.services.git as git_module
 from roboco.exceptions import GitError
+from roboco.services.forge import RepoRef
 from roboco.services.git import GitService
 
 
@@ -71,7 +72,9 @@ async def test_first_allowed_skips_disabled_method(
     monkeypatch.setattr(
         git_module.httpx, "AsyncClient", lambda *_a, **_k: _FakeClient(resp)
     )
-    method = await svc._first_allowed_merge_method("o", "r", "tok", exclude="squash")
+    method = await svc._first_allowed_merge_method(
+        RepoRef("o", "r"), "tok", exclude="squash"
+    )
     assert method == "merge"  # squash disabled + excluded -> next permitted
 
 
@@ -84,7 +87,7 @@ async def test_first_allowed_returns_none_when_lookup_fails(
     monkeypatch.setattr(
         git_module.httpx, "AsyncClient", lambda *_a, **_k: _FakeClient(resp)
     )
-    assert await svc._first_allowed_merge_method("o", "r", "tok") is None
+    assert await svc._first_allowed_merge_method(RepoRef("o", "r"), "tok") is None
 
 
 @pytest.mark.asyncio
@@ -95,7 +98,9 @@ async def test_merge_retries_with_allowed_method_on_405(
     monkeypatch.setattr(
         svc, "_get_project_token_or_raise", AsyncMock(return_value="tok")
     )
-    monkeypatch.setattr(svc, "_parse_github_remote", lambda _ws: ("owner", "repo"))
+    monkeypatch.setattr(
+        svc, "_parse_github_remote", lambda _ws: RepoRef("owner", "repo")
+    )
     monkeypatch.setattr(
         svc, "_delete_pr_branch_best_effort", AsyncMock(return_value=None)
     )
@@ -109,9 +114,7 @@ async def test_merge_retries_with_allowed_method_on_405(
 
     calls: list[str] = []
 
-    async def fake_call(
-        _owner: str, _repo: str, _pr: int, _token: str, method: str
-    ) -> Any:
+    async def fake_call(_repo_ref: RepoRef, _pr: int, _token: str, method: str) -> Any:
         calls.append(method)
         return (
             _resp(200, is_success=True)
@@ -136,7 +139,9 @@ async def test_merge_does_not_retry_when_method_allowed(
     monkeypatch.setattr(
         svc, "_get_project_token_or_raise", AsyncMock(return_value="tok")
     )
-    monkeypatch.setattr(svc, "_parse_github_remote", lambda _ws: ("owner", "repo"))
+    monkeypatch.setattr(
+        svc, "_parse_github_remote", lambda _ws: RepoRef("owner", "repo")
+    )
     monkeypatch.setattr(
         svc, "_delete_pr_branch_best_effort", AsyncMock(return_value=None)
     )
@@ -149,9 +154,7 @@ async def test_merge_does_not_retry_when_method_allowed(
 
     calls: list[str] = []
 
-    async def fake_call(
-        _owner: str, _repo: str, _pr: int, _token: str, method: str
-    ) -> Any:
+    async def fake_call(_repo_ref: RepoRef, _pr: int, _token: str, method: str) -> Any:
         calls.append(method)
         return _resp(200, is_success=True)
 
@@ -176,7 +179,9 @@ async def test_merge_already_merged_pr_is_idempotent_success(
     monkeypatch.setattr(
         svc, "_get_project_token_or_raise", AsyncMock(return_value="tok")
     )
-    monkeypatch.setattr(svc, "_parse_github_remote", lambda _ws: ("owner", "repo"))
+    monkeypatch.setattr(
+        svc, "_parse_github_remote", lambda _ws: RepoRef("owner", "repo")
+    )
     delete_branch = AsyncMock(return_value=None)
     monkeypatch.setattr(svc, "_delete_pr_branch_best_effort", delete_branch)
     monkeypatch.setattr(
@@ -219,7 +224,9 @@ async def test_merge_raises_when_not_merged_and_refused(
     monkeypatch.setattr(
         svc, "_get_project_token_or_raise", AsyncMock(return_value="tok")
     )
-    monkeypatch.setattr(svc, "_parse_github_remote", lambda _ws: ("owner", "repo"))
+    monkeypatch.setattr(
+        svc, "_parse_github_remote", lambda _ws: RepoRef("owner", "repo")
+    )
     delete_branch = AsyncMock(return_value=None)
     monkeypatch.setattr(svc, "_delete_pr_branch_best_effort", delete_branch)
     monkeypatch.setattr(