master planner: wire user-locked topology_kind through chat + scaffold

Frontend: send topologyKind to /api/planner/chat so the planner's user
prompt gets a USER-LOCKED TOPOLOGY block telling Opus to use it verbatim.
On buildTeam, override proposal.topology_kind with the user's pick
(belt-and-braces — if the planner ignored the lock, we still ship the
right shape). Proposal chip renders the effective kind in a lavender
tint when it was overridden, with a hover title showing what was
replaced.

Backend PlannerChatRequest gains an optional topology_kind. Empty /
absent = planner picks. Not honored for 'swarm' mode (swarm planner
doesn't take a topology kind).

crates/cm-api/src/routes/planner.rs

@@ -54,6 +54,11 @@ pub struct PlannerChatRequest {
     /// Deploy mode: specialists | team | swarm | scheduled | triggered (default specialists).
     #[serde(default)]
     pub mode: String,
+    /// User-locked topology from the gallery. When set the planner is told to
+    /// use this kind verbatim (no rewrite). Ignored for `swarm` mode (the swarm
+    /// planner doesn't take a topology kind).
+    #[serde(default)]
+    pub topology_kind: Option<String>,
 }
 
 const SPECIALISTS_NOTE: &str = "\n\nMODE: Specialists. Propose a TIGHTLY-SCOPED group of 2 or 3 DOMAIN \
@@ -113,7 +118,15 @@ pub async fn planner_chat(
         let convo = body.messages.iter()
             .map(|m| format!("{}: {}", if m.role == "user" { "USER" } else { "PLANNER" }, m.content))
             .collect::<Vec<_>>().join("\n\n");
-        let user_prompt = format!("{hierarchy}\n\n=== CONVERSATION ===\n{convo}\n\nRespond now (JSON only).");
+        let topology_lock = match body.topology_kind.as_deref() {
+            Some(k) if !k.is_empty() && body.mode != "swarm" => format!(
+                "\n\n=== USER-LOCKED TOPOLOGY ===\nThe user has selected topology_kind='{k}' from the gallery. \
+                 Use this kind verbatim in the proposal; do NOT choose a different one. Tailor the roles + \
+                 member count to work well within this shape."
+            ),
+            _ => String::new(),
+        };
+        let user_prompt = format!("{hierarchy}{topology_lock}\n\n=== CONVERSATION ===\n{convo}\n\nRespond now (JSON only).");
         let system = planner_system_for(&body.mode);
         let raw = match runtime.complete(&system, &user_prompt, "claude-opus-4-8", 8000, true).await {
             Ok(t) => t,