U12: the LAST triage guard — Plan was offered on executing cards named triage (#2664)

The final `column === "triage"` in production source, and it was a live
defect rather than dead vocabulary.

## The defect

`isPreExecutionHoldColumn` ORed the legacy id with the traits
**unconditionally**:

```ts
return column === "triage" || flags?.intake === true || flags?.hold === true;
```

That is not a fallback. A resolved column merely *named* `triage`
answered true even when its own traits said work was underway — so the
context menu offered **Plan**, which re-plans, on a card that is already
executing.

Now flags-first, with the id as the documented no-metadata answer.

## Why the file's earlier conversion missed it

Every existing case in `TaskContextMenu.test.tsx` passes a column with
**no flags**, or with `hold`/`intake` set. All of them agree under both
forms, so the suite could not distinguish them. Nothing exercised a
column whose **name and traits disagree**, which is the only shape that
separates an OR from a fallback.

Three new cases cover it. Revert check: restoring the OR form fails the
first one — Plan reappears on a mid-flight card.

## The asymmetry is preserved, and now tested

The degraded set stays `{triage}` **alone**, deliberately not the
`{todo, triage}` used by `isPreImplementationColumnRole`. That helper
drives the preserve-progress prompt, where a flagless `todo` *should*
prompt because losing steps is unrecoverable. This drives Plan, where a
flagless `todo` must **not** offer to re-plan a card that may already be
planned. The file documented that difference; nothing asserted it. Now a
test does.

## On reaching zero honestly

The surviving literal is marked `DELIBERATE-LITERAL`. It is the degraded
answer, not an unconverted guard — there is no trait to read when
`flags` is `undefined`, which happens during first paint and for a card
in a column its workflow no longer declares. Deleting it would silently
withdraw Plan from exactly the stranded cards that most need
re-planning.

So **`triage → 0` means "no unconverted guards remain", not "the string
is gone"**, and I would rather say that than move a number by deleting a
fallback.

| branch | triage |
|---|---:|
| `origin/main` | 5 |
| this PR | **4** |
| #2655 (flag resolution, removes 4 in `moves.ts`) | 1 → **0** combined
|

I found it with the census's own AST classifier rather than grep — my
grep of the same tree returned only comment prose and would have had me
report the bar as met while a real defect sat in
`TaskContextMenu.tsx:179`.

## Verification

`pnpm lint` clean. `pnpm test:gate` green (10 / 158 / 487 / 71). `pnpm
check:lifecycle-columns` exits 0 with the baseline re-recorded in this
PR (column 769 → 768, deliberate 12 → 13). `tsc -p tsconfig.app.json`
clean. `TaskContextMenu.test.tsx` 18/18.

Depends on nothing; stacks cleanly with #2655 and #2661.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/lib/lifecycle-column-census-baseline.json

@@ -1,10 +1,10 @@
 {
   "generatedFrom": "node scripts/lifecycle-column-census.mjs --strict --update-baseline",
   "totals": {
-    "column": 769,
+    "column": 768,
     "role": 5,
     "status": 187,
-    "deliberate": 12
+    "deliberate": 13
   },
   "byColumnId": {
     "done": 201,
@@ -12,7 +12,7 @@
     "in-review": 209,
     "archived": 148,
     "todo": 60,
-    "triage": 5
+    "triage": 4
   },
   "byFile": {
     "packages/engine/src/self-healing.ts": 110,
@@ -24,9 +24,9 @@
     "packages/dashboard/src/routes/register-task-workflow-routes.ts": 20,
     "packages/core/src/store.ts": 12,
     "packages/engine/src/project-engine.ts": 12,
-    "packages/dashboard/app/components/TaskContextMenu.tsx": 10,
     "packages/engine/src/mission-execution-loop.ts": 10,
     "packages/core/src/task-store/async-comments-attachments.ts": 9,
+    "packages/dashboard/app/components/TaskContextMenu.tsx": 9,
     "packages/dashboard/src/github-tracking-comments.ts": 9,
     "packages/dashboard/src/github-tracking-reconciler.ts": 9,
     "packages/engine/src/notification/notification-service.ts": 9,