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>

panel/src/components/projects/edit-project-dialog.tsx

@@ -30,15 +30,6 @@ import { Team, type ProjectUpdate, type Project } from "@/types";
 import { EnvironmentLadderEditor } from "@/components/projects/environment-ladder-editor";
 import { validateLadder } from "@/components/projects/ladder-validation";
 import { HelpTip } from "@/components/ui/help-tip";
-import { Badge } from "@/components/ui/badge";
-
-// A null git_provider means "not yet stamped" (pre-Phase-0 project or a
-// non-github.com host awaiting an explicit choice) — RoboCo is GitHub-only
-// today either way, so the badge falls back to "GitHub" rather than "Unknown".
-function forgeLabel(gitProvider: string | null): string {
-  if (!gitProvider) return "GitHub";
-  return gitProvider.charAt(0).toUpperCase() + gitProvider.slice(1);
-}
 
 const cells: { value: Team; label: string }[] = [
   { value: Team.BACKEND, label: "Backend" },
@@ -136,6 +127,7 @@ function EditProjectForm({
   // Initialize form state from project
   const [name, setName] = useState(project.name);
   const [gitUrl, setGitUrl] = useState(project.git_url);
+  const [gitProvider, setGitProvider] = useState(project.git_provider ?? "auto");
   const [assignedCell, setAssignedCell] = useState(project.assigned_cell);
   const [defaultBranch, setDefaultBranch] = useState(project.default_branch);
   const [environments, setEnvironments] = useState(project.environments ?? null);
@@ -219,6 +211,7 @@ function EditProjectForm({
     const updates: ProjectUpdate = {
       name,
       git_url: gitUrl,
+      git_provider: gitProvider === "auto" ? null : gitProvider,
       assigned_cell: assignedCell,
       default_branch: defaultBranch || "main",
       environments,
@@ -317,17 +310,22 @@ function EditProjectForm({
           />
         </div>
 
-        {/* Forge (read-only — GitHub-only today) */}
+        {/* Forge provider */}
         <div className="grid gap-2">
-          <HelpTip label="Auto-detected from the Git URL's host; RoboCo's PR/CI/review surface is GitHub-only today. GitLab & Gitea support planned.">
+          <HelpTip label="Which forge API serves PR/CI/review operations. Auto-detect covers github.com; a self-hosted Gitea instance (or GitHub Enterprise) must be set explicitly — the host comes from the Git URL. GitLab support is planned.">
             <Label>Forge</Label>
           </HelpTip>
-          <div>
-            <Badge variant="secondary">{forgeLabel(project.git_provider)}</Badge>
-          </div>
-          <p className="text-xs text-muted-foreground">
-            GitLab & Gitea support planned.
-          </p>
+          <Select value={gitProvider} onValueChange={setGitProvider}>
+            <SelectTrigger>
+              <SelectValue placeholder="Auto-detect" />
+            </SelectTrigger>
+            <SelectContent>
+              <SelectItem value="auto">Auto-detect (github.com)</SelectItem>
+              <SelectItem value="github">GitHub / GitHub Enterprise</SelectItem>
+              <SelectItem value="gitea">Gitea (self-hosted)</SelectItem>
+              <SelectItem value="gitlab">GitLab (gitlab.com / self-hosted)</SelectItem>
+            </SelectContent>
+          </Select>
         </div>
 
         {/* Git Token Section */}