fix(notepad-guard,start-work): wire dispatch and match .omo paths

notepad-write-guard:
- The hook was created by create-tool-guard-hooks but tool-execute-before
  never invoked it, so the guard was inert.
- It also only matched .sisyphus/notepads, missing the current
  .omo/notepads layout introduced by the workspace migration.
- Add the dispatch call alongside writeExistingFileGuard, and extend
  NOTEPAD_ROOTS to cover both paths via normalize() + sep. New
  integration test pins the wire and the .omo block; the existing unit
  test now asserts both paths.

start-work session-plan-affinity:
- PLAN_PATH_PATTERN only matched .sisyphus/plans, so sessions referring
  to plans under .omo/plans returned null and start-work missed the
  current session's own plan.
- Extend the regex to .(sisyphus|omo)/plans and add findPrometheusPlans
  in packages/boulder-state to scan both directories during the
  transition. New regression test pins .omo/plans matching; legacy
  .sisyphus/plans coverage preserved.

src/hooks/start-work/session-plan-affinity.ts

@@ -3,7 +3,7 @@ import type { PluginInput } from "@opencode-ai/plugin"
 import { normalizeSDKResponse } from "../../shared"
 import { log } from "../../shared/logger"
 
-const PLAN_PATH_PATTERN = /[A-Za-z0-9_./\\:-]*\.sisyphus[\\/]plans[\\/][A-Za-z0-9._/\\-]+\.md/gi
+const PLAN_PATH_PATTERN = /[A-Za-z0-9_./\\:-]*\.(?:sisyphus|omo)[\\/]plans[\\/][A-Za-z0-9._/\\-]+\.md/gi
 
 interface SessionMessagePart {
   text?: string