[codex] Add issue subtree pause, cancel, and restore controls (#4332)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies.
> - This branch extends the issue control-plane so board operators can
pause, cancel, and later restore whole issue subtrees while keeping
descendant execution and wake behavior coherent.
> - That required new hold state in the database, shared contracts,
server routes/services, and issue detail UI controls so subtree actions
are durable and auditable instead of ad hoc.
> - While this branch was in flight, `master` advanced with new
environment lifecycle work, including a new `0065_environments`
migration.
> - Before opening the PR, this branch had to be rebased onto
`paperclipai/paperclip:master` without losing the existing
subtree-control work or leaving conflicting migration numbering behind.
> - This pull request rebases the subtree pause/cancel/restore feature
cleanly onto current `master`, renumbers the hold migration to
`0066_issue_tree_holds`, and preserves the full branch diff in a single
PR.
> - The benefit is that reviewers get one clean, mergeable PR for the
subtree-control feature instead of stale branch history with migration
conflicts.

## What Changed

- Added durable issue subtree hold data structures, shared
API/types/validators, server routes/services, and UI flows for subtree
pause, cancel, and restore operations.
- Added server and UI coverage for subtree previewing, hold
creation/release, dependency-aware scheduling under holds, and issue
detail subtree controls.
- Rebased the branch onto current `paperclipai/paperclip:master` and
renumbered the branch migration from `0065_issue_tree_holds` to
`0066_issue_tree_holds` so it no longer conflicts with upstream
`0065_environments`.
- Added a small follow-up commit that makes restore requests return `200
OK` explicitly while keeping pause/cancel hold creation at `201
Created`, and updated the route test to match that contract.

## Verification

- `pnpm --filter @paperclipai/db typecheck`
- `pnpm --filter @paperclipai/shared typecheck`
- `pnpm --filter @paperclipai/server typecheck`
- `pnpm --filter @paperclipai/ui typecheck`
- `cd server && pnpm exec vitest run
src/__tests__/issue-tree-control-routes.test.ts
src/__tests__/issue-tree-control-service.test.ts
src/__tests__/issue-tree-control-service-unit.test.ts
src/__tests__/heartbeat-dependency-scheduling.test.ts`
- `cd ui && pnpm exec vitest run src/components/IssueChatThread.test.tsx
src/pages/IssueDetail.test.tsx`

## Risks

- This is a broad cross-layer change touching DB/schema, shared
contracts, server orchestration, and UI; regressions are most likely
around subtree status restoration or wake suppression/resume edge cases.
- The migration was renumbered during PR prep to avoid the new upstream
`0065_environments` conflict. Reviewers should confirm the final
`0066_issue_tree_holds` ordering is the only hold-related migration that
lands.
- The issue-tree restore endpoint now responds with `200` instead of
relying on implicit behavior, which is semantically better for a restore
operation but still changes an API detail that clients or tests could
have assumed.

> 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 coding agent in the Paperclip Codex runtime (GPT-5-class
tool-using coding model; exact deployment ID/context window is not
exposed inside this session).

## 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
- [ ] If this change affects the UI, I have included before/after
screenshots
- [ ] 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/components/IssueChatThread.tsx

@@ -227,6 +227,7 @@ interface IssueChatComposerProps {
   mentions?: MentionOption[];
   agentMap?: Map<string, Agent>;
   composerDisabledReason?: string | null;
+  composerHint?: string | null;
   issueStatus?: string;
 }
 
@@ -265,6 +266,7 @@ interface IssueChatThreadProps {
   suggestedAssigneeValue?: string;
   mentions?: MentionOption[];
   composerDisabledReason?: string | null;
+  composerHint?: string | null;
   showComposer?: boolean;
   showJumpToLatest?: boolean;
   emptyMessage?: string;
@@ -1153,6 +1155,8 @@ function IssueChatUserMessage({ message }: { message: ThreadMessage }) {
   const authorName = typeof custom.authorName === "string" ? custom.authorName : null;
   const authorUserId = typeof custom.authorUserId === "string" ? custom.authorUserId : null;
   const queued = custom.queueState === "queued" || custom.clientStatus === "queued";
+  const queueReason = typeof custom.queueReason === "string" ? custom.queueReason : null;
+  const queueBadgeLabel = queueReason === "hold" ? "\u23f8 Deferred wake" : "Queued";
   const pending = custom.clientStatus === "pending";
   const queueTargetRunId = typeof custom.queueTargetRunId === "string" ? custom.queueTargetRunId : null;
   const [copied, setCopied] = useState(false);
@@ -1189,7 +1193,7 @@ function IssueChatUserMessage({ message }: { message: ThreadMessage }) {
         {queued ? (
           <div className="mb-1.5 flex items-center gap-2">
             <span className="inline-flex items-center rounded-full border border-amber-400/60 bg-amber-100/70 px-2 py-0.5 text-[10px] font-medium uppercase tracking-[0.14em] text-amber-800 dark:border-amber-400/40 dark:bg-amber-500/20 dark:text-amber-200">
-              Queued
+              {queueBadgeLabel}
             </span>
             {queueTargetRunId && onInterruptQueued ? (
               <Button
@@ -1910,6 +1914,7 @@ const IssueChatComposer = forwardRef<IssueChatComposerHandle, IssueChatComposerP
   mentions = [],
   agentMap,
   composerDisabledReason = null,
+  composerHint = null,
   issueStatus,
 }, forwardedRef) {
   const api = useAui();
@@ -2068,6 +2073,12 @@ const IssueChatComposer = forwardRef<IssueChatComposerHandle, IssueChatComposerP
         contentClassName="min-h-[72px] max-h-[28dvh] overflow-y-auto pr-1 text-sm scrollbar-auto-hide"
       />
 
+      {composerHint ? (
+        <div className="inline-flex items-center rounded-full border border-border/70 bg-muted/30 px-2 py-1 text-[11px] text-muted-foreground">
+          {composerHint}
+        </div>
+      ) : null}
+
       <div className="flex flex-wrap items-center justify-end gap-3">
         {(onImageUpload || onAttachImage) ? (
           <div className="mr-auto flex items-center gap-3">
@@ -2168,6 +2179,7 @@ export function IssueChatThread({
   suggestedAssigneeValue,
   mentions = [],
   composerDisabledReason = null,
+  composerHint = null,
   showComposer = true,
   showJumpToLatest,
   emptyMessage,
@@ -2468,6 +2480,7 @@ export function IssueChatThread({
               mentions={mentions}
               agentMap={agentMap}
               composerDisabledReason={composerDisabledReason}
+              composerHint={composerHint}
               issueStatus={issueStatus}
             />
           </div>