research pipeline v2: topology-aware start + persisted draft

Three connected changes that turn "Start research" from a status
flip into a real pipeline that produces a reviewable artifact:

- Migration 0036: adds research_topics.topology_kind (default
  'hub_spoke') and a new research_outcomes table
  (id, topic_id, version DESC, body_md, produced_by_run_id, created_at)
  so each run's final synthesis is versioned and persistent.

- Wizard now has a topology picker in the Outcome step —
  hub_spoke / pipeline / hierarchical / star_moe — with copy that
  steers users to the right shape (Pipeline for research → distill
  → analyze → implement rosters, hub_spoke for the coordinator-
  and-specialists default).

- start_topic reads the chosen topology_kind, parses it into a
  cm_topology::TopologyKind, and dispatches a per-shape coordinator
  prompt via build_coordinator_task. Pipeline explicitly tells
  stage 1 not to write the final artifact and propagates a
  "final stage MUST emit a complete markdown document with
  measurable acceptance criteria" instruction downstream. The
  graph builder is called with the topology the user actually
  picked instead of hard-coded HubSpoke.

- topology_worker::freeze_research_outcome fires after every
  successful complete(). It looks up research_topic_id on the run;
  if set and final_output is non-empty, it inserts a new
  research_outcomes row (version auto-derived server-side via
  coalesce(max(version), 0) + 1). Best-effort — a DB hiccup logs
  but doesn't fail the run.

- TopicDetail now includes topology_kind and latest_outcome.
  ResearchCanvas swaps in the outcome's body_md (rendered as
  pre-wrap markdown, versioned header, produced-at timestamp)
  whenever an outcome exists; the original prompt collapses into
  an "Original prompt" <details> below so it's still one click
  away. Pre-run topics still show the description as before.

Follow-ups still open: reject-with-revision loop feeding the
coordinator, publishing → published transition + real artifact
export (md / pdf), and an approvals inbox surface for reviewers.

.sqlx/query-dc9b55c84dad42d5b397353d3b5d5ef5af28cc8c51802526c70b8b2f6e4c0c64.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT research_topic_id FROM topology_runs WHERE id = $1",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "research_topic_id",
+        "type_info": "Uuid"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      true
+    ]
+  },
+  "hash": "dc9b55c84dad42d5b397353d3b5d5ef5af28cc8c51802526c70b8b2f6e4c0c64"
+}