loops: repo picker + agent/team/org staffing + sidebar edit/delete

Adds the missing pieces the wizard needed and the sidebar controls
around it:

- LoopsWizard is now a 6-step flow (identity → repo → task/topology
  → triggers → repeat → assign agents) plus the existing secrets
  card. ResearchWizard picks up the same repo step and a hard gate
  when the workspace has zero agents.
- New LoopStaffingStep with three tabs — Individual / Team /
  Organization — that mix freely per loop; selections persist via
  new loop_agents / loop_teams / loop_orgs join tables (0035
  migration), each cascading on loop_id so hard-delete stays a
  single-row DELETE.
- Backend CreateLoopRequest / UpdateLoopRequest accept the three
  lists and apply_staffing does a transactional replace-all;
  list_loops / get_loop hydrate the lists via a flattened
  LoopWithStaffing response.
- LoopsList sidebar gains per-row enable/disable, edit (reopens the
  wizard prefilled with the current loop, PATCHes on submit), and
  delete with an inline confirm.
- NoAgentsGate blocks launching a loop or research topic from a
  workspace with no roster; the sidebar `+` buttons also disable
  with a tooltip pointing at the TEAM tier.

Not yet wired: the run driver still fills role slots from the
workspace-wide pool; teaching enqueue_iteration to prefer
loop_agents/loop_teams/loop_orgs is a follow-up.

.sqlx/query-47c1cee8591250819d22e87058c6011bebb77eaf93c1cfa2535db42221d8ecf3.json

@@ -1,34 +0,0 @@
-{
-  "db_name": "PostgreSQL",
-  "query": "SELECT tokens_in, tokens_out, credits FROM usage_events\n               WHERE workspace_id = $1",
-  "describe": {
-    "columns": [
-      {
-        "ordinal": 0,
-        "name": "tokens_in",
-        "type_info": "Int8"
-      },
-      {
-        "ordinal": 1,
-        "name": "tokens_out",
-        "type_info": "Int8"
-      },
-      {
-        "ordinal": 2,
-        "name": "credits",
-        "type_info": "Numeric"
-      }
-    ],
-    "parameters": {
-      "Left": [
-        "Uuid"
-      ]
-    },
-    "nullable": [
-      false,
-      false,
-      false
-    ]
-  },
-  "hash": "47c1cee8591250819d22e87058c6011bebb77eaf93c1cfa2535db42221d8ecf3"
-}