feat(coach): scope filter + conversation provenance on the plans list

Groundwork for the plan confirm/manage UI. The CoachPlan pipeline has been
complete on the server since v1.21.3/v1.22 — extractor writes proposals
(status "proposed", per-user cap, de-dup, encrypted prose), the PATCH
confirms proposed -> active, buildCoachPlansBlock injects the top-6 active
plans into the snapshot, and the review sweep drives the reviewDate
lifecycle — but no surface ever listed or confirmed a proposal, so the
extraction spend had no user-visible outcome.

Two additive contract changes the UI needs:
- GET /api/coach/plans accepts ?scope=open|past|all (open = proposed +
  active + review_due, past = met + abandoned + reviewed, all = no status
  clause) so the management page reads its ledger in one round-trip.
  Mutually exclusive with ?status=; both omitted keeps today's
  non-terminal default unchanged.
- Plan items now carry sourceConversationId so the chat thread can show
  only the proposals born in the open conversation.

OpenAPI regenerated; route tests cover the scope mappings, the
status+scope 422, and the provenance passthrough.

src/lib/openapi/routes/coach.ts

@@ -15,6 +15,7 @@ import {
 import { COACH_FACT_CATEGORIES } from "@/lib/ai/coach/facts";
 import { COACH_PLAN_STATUSES } from "@/lib/ai/coach/plans";
 import {
+  COACH_PLAN_SCOPES,
   coachPlanPatchSchema,
   coachPlansListQuerySchema,
 } from "@/lib/validations/coach-plan";
@@ -283,6 +284,12 @@ const coachPlanItem = z
       .datetime({ offset: true })
       .nullable()
       .describe("Optional check-in checkpoint; null when none."),
+    sourceConversationId: z
+      .string()
+      .nullable()
+      .describe(
+        "Id of the conversation the proposal was extracted from; null for a plan without conversation provenance. Lets a chat surface show only the proposals born in the open thread.",
+      ),
     createdAt: z.iso.datetime({ offset: true }),
     updatedAt: z.iso.datetime({ offset: true }),
   })
@@ -321,7 +328,7 @@ coachPlanPatchSchema.meta({
 coachPlansListQuerySchema.meta({
   id: "CoachPlansListQuery",
   description:
-    "Optional `?status=` filter for the plans list (proposed | active | met | abandoned). Omitted returns the non-terminal set (proposed + active).",
+    "Optional `?status=` filter for the plans list (a single lifecycle status), or `?scope=` for a named group (open = proposed + active + review_due, past = met + abandoned + reviewed, all = every non-deleted plan). Mutually exclusive. Both omitted returns the non-terminal set (proposed + active).",
 });
 
 // ── Coach episodic reminders (v1.22 B2/B6) ──────────────────────────────
@@ -1021,7 +1028,7 @@ export const coachPaths: NonNullable<ZodOpenApiObject["paths"]> = {
       tags: ["Insights"],
       summary: "List the caller's Coach goal / if-then plans",
       description:
-        'v1.21.3 (B1) — returns the durable plans the Coach has proposed for the caller, newest first, each decrypted on the fly. A plan is an "if-then" implementation intention tied to one metric, with an optional target. The Coach extractor writes a plan as `proposed`; only `PATCH /api/coach/plans/{id}` activates it. Pass `?status=` to filter (proposed | active | met | abandoned); omitted returns the non-terminal set (proposed + active). Coach-gated (`requireModuleEnabled("coach")`); a disabled surface 403s. Auth via cookie or Bearer; the owner is always narrowed from the session, never the body. Undecryptable rows are omitted rather than failing the read.',
+        'v1.21.3 (B1) — returns the durable plans the Coach has proposed for the caller, newest first, each decrypted on the fly. A plan is an "if-then" implementation intention tied to one metric, with an optional target. The Coach extractor writes a plan as `proposed`; only `PATCH /api/coach/plans/{id}` activates it. Pass `?status=` to filter to one lifecycle status, or `?scope=` for a named group (open = proposed + active + review_due, past = met + abandoned + reviewed, all = every non-deleted plan) — mutually exclusive. Both omitted returns the non-terminal set (proposed + active). Coach-gated (`requireModuleEnabled("coach")`); a disabled surface 403s. Auth via cookie or Bearer; the owner is always narrowed from the session, never the body. Undecryptable rows are omitted rather than failing the read.',
       parameters: [
         {
           name: "status",
@@ -1029,7 +1036,15 @@ export const coachPaths: NonNullable<ZodOpenApiObject["paths"]> = {
           required: false,
           schema: { type: "string", enum: [...COACH_PLAN_STATUSES] },
           description:
-            "Filter to a single lifecycle status. Omit for the non-terminal set (proposed + active).",
+            "Filter to a single lifecycle status. Mutually exclusive with `scope`. Omit both for the non-terminal set (proposed + active).",
+        },
+        {
+          name: "scope",
+          in: "query",
+          required: false,
+          schema: { type: "string", enum: [...COACH_PLAN_SCOPES] },
+          description:
+            "Named status group: open (proposed + active + review_due), past (met + abandoned + reviewed), or all. Mutually exclusive with `status`.",
         },
       ],
       responses: {