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.

crates/cm-db/src/repo/research_outcomes.rs

@@ -0,0 +1,81 @@
+//! Persisted research artifacts — one row per run's final synthesis. When
+//! `topology_worker` completes a run tagged with a `research_topic_id`, it
+//! extracts the orchestrator's `RunRecord.final_output` and calls
+//! [`insert`] here. The frontend canvas then renders the latest outcome
+//! instead of the topic description when the topic has moved past
+//! `standby`, so reviewers see the actual draft.
+//!
+//! Version is per-topic and monotonically increasing so reject-with-
+//! revision loops accumulate history rather than clobber prior drafts.
+
+use serde::{Deserialize, Serialize};
+use sqlx::PgPool;
+use time::OffsetDateTime;
+use uuid::Uuid;
+
+use crate::DbError;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Outcome {
+    pub id: Uuid,
+    pub topic_id: Uuid,
+    pub version: i32,
+    pub body_md: String,
+    pub produced_by_run_id: Option<Uuid>,
+    pub created_at: OffsetDateTime,
+}
+
+/// Insert a new outcome. Version is derived server-side as `max(version) + 1`
+/// for the topic (starting at 1) so callers never need to know the current
+/// count. Returns the persisted row.
+pub async fn insert(
+    pool: &PgPool,
+    topic_id: Uuid,
+    body_md: &str,
+    produced_by_run_id: Option<Uuid>,
+) -> Result<Outcome, DbError> {
+    let id = Uuid::now_v7();
+    let row = sqlx::query!(
+        "INSERT INTO research_outcomes (id, topic_id, version, body_md, produced_by_run_id)
+         SELECT $1, $2, coalesce(max(version), 0) + 1, $3, $4
+           FROM research_outcomes
+          WHERE topic_id = $2
+         RETURNING id, topic_id, version, body_md, produced_by_run_id, created_at",
+        id,
+        topic_id,
+        body_md,
+        produced_by_run_id,
+    )
+    .fetch_one(pool)
+    .await?;
+    Ok(Outcome {
+        id: row.id,
+        topic_id: row.topic_id,
+        version: row.version,
+        body_md: row.body_md,
+        produced_by_run_id: row.produced_by_run_id,
+        created_at: row.created_at,
+    })
+}
+
+/// Newest outcome for a topic, or `None` if no run has completed yet.
+pub async fn latest(pool: &PgPool, topic_id: Uuid) -> Result<Option<Outcome>, DbError> {
+    let row = sqlx::query!(
+        "SELECT id, topic_id, version, body_md, produced_by_run_id, created_at
+           FROM research_outcomes
+          WHERE topic_id = $1
+          ORDER BY version DESC
+          LIMIT 1",
+        topic_id,
+    )
+    .fetch_optional(pool)
+    .await?;
+    Ok(row.map(|r| Outcome {
+        id: r.id,
+        topic_id: r.topic_id,
+        version: r.version,
+        body_md: r.body_md,
+        produced_by_run_id: r.produced_by_run_id,
+        created_at: r.created_at,
+    }))
+}