feat(board): materialize program items as Main-PM roots, make reports actionable (#711)

Two coupled gaps in the Board Program output path.

Approved items were created unowned and in BACKLOG. Nothing dispatches
BACKLOG, and once activated a cell PM claimed the parentless task as a root,
where _cell_pm_complete resolves its merge target through
resolve_parent_branch — which for a parentless task falls through to the
project head rung. The result was a cell branch merging straight into the
trunk, bypassing the Main-PM root, the root->master PR and the CEO gate
(live: PRs #703 and #704 both targeted slave directly).

All eight materializers now create a PENDING, main-pm-assigned root with
team=Team.MAIN_PM, matching what approve_and_start does for an intake draft.
The team is load-bearing, not cosmetic: _next_hint_pr_fail,
_deliver_pr_fail_to_owner, delegate's wave-chain dispatch and the PR layer
label all key on it, and a cell-teamed root drops the 'do NOT re-submit the
root' steer that exists because of PR #138's infinite pr_fail loop. The
item's own cell survives as a delegation hint in the description, which is
what the Main PM's briefing renders.

Periscope, Sentinel and Coroner produced artifacts with no way to act on
them — three panel surfaces carried explicit 'no approve/reject UI' comments
while each item already held a machine-readable suggested action. They now
have per-item approve and dismiss, modelled on the roadmap queue: idempotent
per item, CEO-gated, deep-copy-before-mutate so SQLAlchemy's dirty check
still fires, and every decision recorded through record_decision so it
reaches the next cycle's prompt. Approving materializes through the same
corrected Main-PM-owned path.

Target project resolves to each engine's own existing anchor — RoboCo's
project for Periscope and Sentinel, the incident's project for Coroner — and
fails with a clean invalid_state naming what is unresolvable rather than
guessing at a repo.

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

tests/integration/test_prompter_redraft.py

@@ -2,13 +2,14 @@ from __future__ import annotations
 
 from types import SimpleNamespace
 from typing import TYPE_CHECKING, cast
-from uuid import uuid4
+from uuid import UUID, uuid4
 
 import pytest
 import pytest_asyncio
 from roboco.db.tables import AgentTable, ProjectTable, TaskTable
 from roboco.models import AgentRole, AgentStatus, Team
 from roboco.models.base import TaskNature, TaskStatus, TaskType
+from roboco.seeds.initial_data import AGENT_UUIDS
 from roboco.services.base import NotFoundError
 from roboco.services.prompter import (
     PrompterService,
@@ -138,9 +139,28 @@ async def redraft_setup(db_session: AsyncSession) -> AsyncIterator[dict]:
             metrics={},
         )
 
-    main_pm = _agent("main-pm", AgentRole.MAIN_PM)
+    # merge() with the fixed AGENT_UUIDS id: idempotent whether or not another
+    # test already committed this exact "main-pm"-slugged row on the shared
+    # session-scoped test DB (mirrors test_prompter.py's identical upsert) —
+    # an unconditional insert with a fresh random id here would collide with
+    # any other test's row on the slug's unique index.
+    main_pm = await db_session.merge(
+        AgentTable(
+            id=UUID(AGENT_UUIDS["main-pm"]),
+            name="main-pm",
+            slug="main-pm",
+            role=AgentRole.MAIN_PM,
+            team=None,
+            status=AgentStatus.ACTIVE,
+            model_config={},
+            system_prompt="x",
+            capabilities=[],
+            permissions={},
+            metrics={},
+        )
+    )
     po = _agent(f"product-owner-{uuid4().hex[:4]}", AgentRole.PRODUCT_OWNER)
-    db_session.add_all([main_pm, po])
+    db_session.add(po)
     await db_session.flush()
     project = ProjectTable(
         id=uuid4(),