feat(lanes): lane runtime UI, docs, and env additions (A1+A2)

Client-side rendering for the per-lane runtime facts (slot, ports,
database, Redis index, service liveness) added in the server-side
A1/A2 work, plus the doc updates (README, CLAUDE.md, docs/API.md,
client/server READMEs) describing the new profile.env keys, hook
environment contract, and REST endpoints.

client/README.md

@@ -400,6 +400,9 @@ Server broadcasts these event types over WebSocket:
 | `notification.received` | Notification object | Notification hook |
 | `remote_source.status` | `{ id, status, error?, last_sync_at? }` (`status`: `idle`/`syncing`/`ok`/`error`/`deleted`) | Remote Data Source sync poller + `/api/remote-sources` routes |
 | `remote_data.updated` | `{ sourceId, source, label?, counters?, last_sync_at? }` | Emitted once per successful remote sync; triggers stats/cost/session refetches. The server also broadcasts `session_created` / `session_updated` (and main-agent frames) for each mirrored session so Kanban/Sessions update immediately |
+| `lane_hook_output` | `{ laneId, hook, stream, line }` | One output line from a lane's profile hook, pushed while it still runs. A build can take minutes; `LaneCard` shows the latest line so a boot does not read as a hang |
+| `lane_runtime` | `{ laneId, runtime? , error? }` | A lane's stack finished coming up or failed to. Carries the fresh runtime facts, so a listener need not re-request them |
+| `lane_hook_result` | `{ laneId, hook, code, error? }` | A profile hook exited (`POST /api/lanes/:id/hook/:name`). `code` is `null` when the hook could not be started |
 
 ### EventBus Pattern