wizard: 'fresh coding team' picker for paired coding loop

Second slice of the per-loop-team arc. The paired-coding-loop checkbox
in ResearchWizard step 6 now exposes a two-option picker:

  ⦿ Provision a dedicated coding team (default when the loop is on)
     — fresh 'Coding · <topic>' team row, risk_profile =
       coding_readwrite, clawmates_door in mcp_bundles. Loop's
       team_id is bound at wizard-submit time.
  ○ Reuse the research team (legacy) — no team_id bound; coding
     iterations spawn against the research topic's container.

Frontend
- New codingTeamMode state, radio picker rendered under the checkbox.
- research.ts createTopic body gains paired_coding_team_mode?: 'fresh'|
  'reuse'.

Backend
- CreateTopicRequest gains paired_coding_team_mode: Option<String>.
- materialize_topic_loops takes it through and, when 'fresh', calls
  the new provision_fresh_coding_team helper — inserts a teams row
  via the existing insert_team_with_lifecycle (pipeline kind, same
  graph as the loop), sets its runtime-config via
  set_team_runtime_config, then binds loop.team_id.
- All operations best-effort with stderr logging — a team-provision
  failure leaves the loop functional under the legacy fallback.

Not shipped in this slice (deferred to runtime hookup slice):
- research_container::spawn keyed on team_id → per-team container
- Config template rewrite injecting the team's risk_profile
- Migration of existing paired loops onto their own teams

The plumbing lands now so the wizard's intent is recorded; the
runtime honors it in the next PR.

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

@@ -147,6 +147,14 @@ pub struct CreateTopicRequest {
     /// kind='exec' loop bound to this topic with on_artifact_update.
     #[serde(default)]
     pub create_paired_coding_loop: bool,
+    /// 0045 fold — team disposition for the paired coding loop:
+    ///   Some("fresh") — provision a dedicated coding team with
+    ///                   coding_readwrite risk profile (recommended)
+    ///   Some("reuse") — attach the coding loop to the research team
+    ///                   (legacy behavior, both share one container)
+    ///   None          — treated as "reuse" for backwards compat.
+    #[serde(default)]
+    pub paired_coding_team_mode: Option<String>,
 }
 
 // The wizard sends a denormalized display object for its own UI. Only
@@ -392,6 +400,7 @@ pub async fn create_topic(
             &body.title,
             &sched.mode,
             body.create_paired_coding_loop,
+            body.paired_coding_team_mode.as_deref(),
         )
         .await;
     }