research_topics::create: bag 8 args into a NewTopic struct (fixes clippy)

The prior signature took (pool, workspace_id, title, description,
outcome_kind, topology_kind, repo_id, created_by) — 8 args, one
over the clippy::too_many_arguments ceiling and blocking CI.

Refactor to a NewTopic<'a> input struct mirroring the NewLoop /
NewSubTopology pattern the codebase already uses. Wizard-side
additions like a repo commit branch land as struct fields
instead of cascading into every call site.

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

@@ -44,30 +44,35 @@ pub struct AgentSlot {
     pub role_slot: Option<String>,
 }
 
+/// Fields the wizard collected for a new research topic. Grouped into a
+/// struct so `create` stays under the 7-argument clippy ceiling and future
+/// wizard additions (repo commit-branch, etc.) don't cascade into every
+/// call site.
+pub struct NewTopic<'a> {
+    pub workspace_id: Uuid,
+    pub title: &'a str,
+    pub description: &'a str,
+    pub outcome_kind: &'a str,
+    pub topology_kind: &'a str,
+    pub repo_id: Option<Uuid>,
+    pub created_by: Uuid,
+}
+
 /// Creates a topic in `standby`. Returns the new row's id.
-pub async fn create(
-    pool: &PgPool,
-    workspace_id: Uuid,
-    title: &str,
-    description: &str,
-    outcome_kind: &str,
-    topology_kind: &str,
-    repo_id: Option<Uuid>,
-    created_by: Uuid,
-) -> Result<Uuid, DbError> {
+pub async fn create(pool: &PgPool, input: NewTopic<'_>) -> Result<Uuid, DbError> {
     let id = Uuid::now_v7();
     sqlx::query!(
         "INSERT INTO research_topics
             (id, workspace_id, title, description, outcome_kind, topology_kind, repo_id, status, created_by)
          VALUES ($1, $2, $3, $4, $5, $6, $7, 'standby', $8)",
         id,
-        workspace_id,
-        title,
-        description,
-        outcome_kind,
-        topology_kind,
-        repo_id,
-        created_by,
+        input.workspace_id,
+        input.title,
+        input.description,
+        input.outcome_kind,
+        input.topology_kind,
+        input.repo_id,
+        input.created_by,
     )
     .execute(pool)
     .await?;