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_task_service_transitions.py

@@ -2048,21 +2048,29 @@ async def test_activate_batch_root_subtasks_retypes_code_to_planning(
     when flipping team to main_pm, mirroring approve_and_start, or the
     main_pm+code combo recurs."""
     svc = task_setup["svc"]
-    # approve_and_start resolves the main-pm agent by slug — seed it.
-    main_pm = AgentTable(
-        id=uuid4(),
-        name="Main PM",
-        slug="main-pm",
-        role=AgentRole.MAIN_PM,
-        team=Team.MAIN_PM,
-        status=AgentStatus.ACTIVE,
-        model_config={},
-        system_prompt="main-pm",
-        capabilities=[],
-        permissions={},
-        metrics={},
-    )
-    db_session.add(main_pm)
+    # approve_and_start resolves the main-pm agent by slug — seed it. Keyed
+    # on the fixed foundation UUID + an existence check (mirrors
+    # test_ceo_reject_routes_coordination_task_to_main_pm above): the
+    # cross-test-shared DB already has other tests seeding this exact
+    # "main-pm" slug, and a second unconditional insert with a fresh random
+    # id would collide on the slug's unique index.
+    main_pm_id = UUID(AGENT_UUIDS["main-pm"])
+    if await db_session.get(AgentTable, main_pm_id) is None:
+        db_session.add(
+            AgentTable(
+                id=main_pm_id,
+                name="Main PM",
+                slug="main-pm",
+                role=AgentRole.MAIN_PM,
+                team=Team.MAIN_PM,
+                status=AgentStatus.ACTIVE,
+                model_config={},
+                system_prompt="main-pm",
+                capabilities=[],
+                permissions={},
+                metrics={},
+            )
+        )
     await db_session.flush()
 
     batch = uuid4()