collab-stack: import collab stack with local repairs

Start from the pinned `origin/dev/friel/collab-stack` snapshot and fold in the
local follow-up repairs that made that imported stack usable here: watchdog
spawn/registration plumbing, deferred-tool fallback behavior, collab discovery
fixture alignment, schema mirroring, and subagent-panel fixes.

Original imported source:
- source ref: `refs/remotes/origin/dev/friel/collab-stack`
- source tip: `599ed9dc05eafd116192184bd54a2a55a2c49366`
- original base: `c1d18ceb6f22ae3acd67bbd6badad0f475b31dfc`

.github/workflows/bazel.yml

@@ -131,7 +131,7 @@ jobs:
           key: ${{ steps.prepare_bazel.outputs.repository-cache-key }}
 
   clippy:
-    timeout-minutes: 30
+    timeout-minutes: 60
     strategy:
       fail-fast: false
       matrix: