[codex] Add issue monitor liveness controls (#4988)

## Thinking Path

> - Paperclip is a control plane for autonomous AI companies where work
must stay observable, governable, and recoverable.
> - The task/heartbeat subsystem owns agent execution continuity, issue
state transitions, and visible recovery behavior.
> - Waiting on an external service is not the same as being blocked when
the assignee still owns a future check.
> - The gap was that agents had no first-class one-shot monitor state
for external-service waits, so recovery could look stalled or require ad
hoc comments.
> - This pull request adds bounded issue monitors that can wake the
owner, clear exhausted waits, and produce explicit recovery behavior.
> - It also surfaces monitor status in the board UI and documents when
to use monitors versus `blocked`.
> - The benefit is clearer liveness semantics for asynchronous waits
without weakening single-assignee task ownership.

## What Changed

- Added issue monitor fields, shared types, validators, constants, and
an idempotent `0075` migration for scheduled monitor state.
- Added server-side monitor scheduling, dispatch, recovery bounds,
activity logging, and external-ref redaction.
- Added board/agent route coverage for monitor permissions and child
monitor scheduling.
- Added issue detail/property UI for monitor state, a monitor activity
card, and Storybook stories for review surfaces.
- Documented monitor semantics and recovery policy behavior in
`doc/execution-semantics.md`.
- Addressed Greptile review feedback by preserving monitor state in
skipped-stage builders and making board monitor saves send `scheduledBy:
"board"`.

## Verification

- `pnpm install --frozen-lockfile`
- `pnpm run preflight:workspace-links && pnpm exec vitest run
server/src/__tests__/issue-execution-policy-routes.test.ts
server/src/__tests__/issue-execution-policy.test.ts
server/src/__tests__/issue-monitor-scheduler.test.ts
server/src/__tests__/recovery-classifiers.test.ts
ui/src/components/IssueMonitorActivityCard.test.tsx
ui/src/components/IssueProperties.test.tsx
ui/src/lib/activity-format.test.ts`
- First run passed 5 files and failed to collect 2 server suites because
the worktree was missing the optional `acpx/runtime` dependency.
- After `pnpm install --frozen-lockfile`, reran the 2 failed suites
successfully.
- `pnpm exec vitest run
server/src/__tests__/issue-monitor-scheduler.test.ts
server/src/__tests__/recovery-classifiers.test.ts`
- `pnpm --filter @paperclipai/shared typecheck && pnpm --filter
@paperclipai/db typecheck && pnpm --filter @paperclipai/server typecheck
&& pnpm --filter @paperclipai/ui typecheck`
- `pnpm exec vitest run
server/src/__tests__/issue-execution-policy.test.ts
ui/src/components/IssueProperties.test.tsx`
- `pnpm --filter @paperclipai/server typecheck && pnpm --filter
@paperclipai/ui typecheck`
- `pnpm exec vitest run
ui/src/components/IssueMonitorActivityCard.test.tsx
ui/src/components/IssueProperties.test.tsx`
- `pnpm --filter @paperclipai/ui typecheck`
- Storybook screenshot captured from
`http://127.0.0.1:6006/iframe.html?viewMode=story&id=product-issue-monitor-surfaces--monitor-surfaces`
with Playwright.

## Screenshots

![Issue monitor Storybook
surfaces](https://raw.githubusercontent.com/paperclipai/paperclip/PAP-2945-when-a-task-is-waiting-for-an-_external-service_-what-state-should-it-be-in-and-what-recovery-method-could-it-h/docs/pr-screenshots/pap-2945/monitor-surfaces.png)

## Risks

- Medium: this changes heartbeat recovery behavior for scheduled
external-service waits, so regressions could affect wake timing or
recovery issue creation.
- Migration risk is reduced by using `IF NOT EXISTS` for the new issue
monitor columns and index.
- External monitor references are treated as secret-adjacent and are
intentionally omitted from visible activity/wake payloads.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

- OpenAI Codex, GPT-5 coding agent with repository tool use and terminal
execution.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots or Storybook review surfaces
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

ui/src/lib/activity-format.ts

@@ -33,6 +33,14 @@ const ACTIVITY_ROW_VERBS: Record<string, string> = {
   "issue.document_created": "created document for",
   "issue.document_updated": "updated document on",
   "issue.document_deleted": "deleted document from",
+  "issue.monitor_scheduled": "scheduled monitor on",
+  "issue.monitor_triggered": "triggered monitor for",
+  "issue.monitor_cleared": "cleared monitor on",
+  "issue.monitor_skipped": "skipped monitor for",
+  "issue.monitor_exhausted": "exhausted monitor on",
+  "issue.monitor_recovery_wake_queued": "queued monitor recovery for",
+  "issue.monitor_recovery_issue_created": "created monitor recovery for",
+  "issue.monitor_escalated_to_board": "escalated monitor for",
   "issue.commented": "commented on",
   "issue.deleted": "deleted",
   "agent.created": "created",
@@ -75,6 +83,14 @@ const ISSUE_ACTIVITY_LABELS: Record<string, string> = {
   "issue.document_created": "created a document",
   "issue.document_updated": "updated a document",
   "issue.document_deleted": "deleted a document",
+  "issue.monitor_scheduled": "scheduled a monitor",
+  "issue.monitor_triggered": "triggered a monitor",
+  "issue.monitor_cleared": "cleared a monitor",
+  "issue.monitor_skipped": "skipped a monitor",
+  "issue.monitor_exhausted": "exhausted a monitor",
+  "issue.monitor_recovery_wake_queued": "queued a monitor recovery wake",
+  "issue.monitor_recovery_issue_created": "created a monitor recovery issue",
+  "issue.monitor_escalated_to_board": "escalated a monitor to the board",
   "issue.deleted": "deleted the issue",
   "agent.created": "created an agent",
   "agent.updated": "updated the agent",
@@ -296,6 +312,14 @@ export function formatIssueActivityAction(
   });
   if (structuredChange) return structuredChange;
 
+  if (action.startsWith("issue.monitor_") && details) {
+    const serviceName = typeof details.serviceName === "string" && details.serviceName.trim()
+      ? details.serviceName.trim()
+      : null;
+    const base = ISSUE_ACTIVITY_LABELS[action] ?? action.replace(/[._]/g, " ");
+    return serviceName ? `${base} for ${serviceName}` : base;
+  }
+
   if (
     (action === "issue.document_created" || action === "issue.document_updated" || action === "issue.document_deleted") &&
     details