feat: Claude Code Monitor — lanes, pipelines and a merged workspace

Internal SmartGift build of a Claude Code monitoring dashboard.

Lanes: a durable unit of parallel agent work, one per working directory,
tracked across session restarts. Managed lanes are git worktrees the
dashboard provisions and can reset or remove behind a three-check destroy
guard and a counted preflight; adopted lanes are directories you already
own and are never destroyable.

Pipelines: a lane moves through pipeline stages. A stage the agent declares
with evidence renders green; a stage inferred from the tool-event stream
renders dashed amber and never counts as done. Detection is forward-only
within a 30-minute window, and never writes the declared stage.

Workspace: one page at /run with a lane grid, the selected lane's pipeline,
and a full Claude console behind a disclosure.

plugins/ccam-cost-guard/commands/overspend.md

@@ -0,0 +1,21 @@
+---
+description: List the most expensive sessions pushing your spend up
+argument-hint: "[top-N]"
+---
+
+List the sessions driving Claude Code spend up — the **top $ARGUMENTS** most expensive
+(default top 10 if empty).
+
+1. Fetch a wide slice of sessions:
+   ```
+   curl -s "http://localhost:4820/api/sessions?limit=200"
+   ```
+
+2. Sort the returned sessions by inline `cost` **descending** and take the top N.
+
+3. Print a table — rank, session id/name, `model`, `started_at`, `metadata.turn_count`, and `cost` (USD, 4 decimals). Below it:
+   - **Sum of the top N** and what share of fleet spend they represent (sum top-N `cost` / sum of all `cost`).
+   - Flag any Opus session with a low `turn_count` as a downshift candidate (point to the `model-savings` skill).
+
+If the dashboard is unreachable, tell the user to start it with `npm start` from the
+repo root. Keep it to one table plus two summary lines. Read-only — do not modify anything.