feat(coach): one quiet status line, reply pills and memory notes in the thread

The top of an answer is one line that says what the Coach is doing right
now (thinking, fetching a metric, summarising the readings, writing),
live from the activity frames, with the seconds so far. It never opens
by itself: the trail stays closed while the turn runs, when it asks,
when it stops early, after the answer and after a reload, and opens
only on a tap. Once the answer is in, the line settles into one summary
of lookups and seconds. A table read during the turn shows as a
one-line preview with a sparkline until the answer takes it over.

Clarifying choices, follow-ups and the answers to a fact or plan
proposal share one pattern: quiet pills in the answer's column whose
tap sends the label as the person's own message. The clarification
card and the in-thread plan card are gone. A fact the Coach kept is one
meta line with Undo, an assumption one line with Change. The remember
button on a message now keeps it in the Coach's memory.

src/__tests__/destructive-control-guard.test.ts

@@ -196,9 +196,26 @@ const REGISTRY: DestructiveEntry[] = [
   },
   {
     file: "components/settings/coach-memory-section.tsx",
-    destroys: "one remembered Coach fact, or every one of them",
+    destroys: "every remembered Coach fact at once",
     recovery: "tombstoned-no-restore",
-    confirm: ["ConfirmButton", "AlertDialog"],
+    confirm: ["AlertDialog"],
+  },
+  {
+    file: "components/insights/coach-panel/use-coach-facts.ts",
+    destroys: "one remembered Coach fact",
+    triggers: [
+      "components/settings/coach-memory-section.tsx",
+      "components/insights/coach-panel/memory-note.tsx",
+    ],
+    recovery: "tombstoned-no-restore",
+    confirm: ["ConfirmButton"],
+    unconfirmed: [
+      {
+        control: "Undo on the memory note under an answer — memory-note.tsx",
+        reason:
+          "Undo takes back what the Coach saved a moment ago on its own, from the person's own words in the same turn. Nothing the person wrote is lost: their message stays in the thread and the fact can be kept again with one tap. Asking to confirm an undo would make reversing the Coach dearer than letting it keep something unwanted. Forgetting from the memory list, where a fact may be old and relied on, is confirmed.",
+      },
+    ],
   },
   {
     file: "hooks/use-coach-reminders.ts",
@@ -210,16 +227,12 @@ const REGISTRY: DestructiveEntry[] = [
   {
     file: "hooks/use-coach-plans.ts",
     destroys: "a Coach plan and the record of how it went",
-    triggers: [
-      "app/coach/plans/page.tsx",
-      "components/insights/coach-panel/plan-proposal-card.tsx",
-    ],
+    triggers: ["app/coach/plans/page.tsx"],
     recovery: "tombstoned-no-restore",
     confirm: ["ConfirmButton"],
     unconfirmed: [
       {
-        control:
-          "decline a PROPOSED plan — app/coach/plans/page.tsx and plan-proposal-card.tsx",
+        control: "decline a PROPOSED plan — app/coach/plans/page.tsx",
         reason:
           "Declining is the negative half of an accept/decline pair the assistant just offered; the person has invested nothing in a proposal they never adopted, and the same suggestion re-derives on a later turn. Confirming a refusal would make saying no more expensive than saying yes. The delete of a plan the person actually RAN is confirmed, and that is the one carrying history.",
       },

src/__tests__/success-affordance-guard.test.ts

@@ -190,9 +190,6 @@ const PINNED_AFFORDANCES: Record<
   "src/components/insights/coach-panel/history-rail.tsx": {
     "toast.success": 1,
   },
-  "src/components/insights/coach-panel/plan-proposal-card.tsx": {
-    "text-success": 1,
-  },
   "src/components/insights/coach-panel/reminder-suggestion-card.tsx": {
     "text-success": 1,
   },