wave 7: the prober reads its map — graph-context injection dies whole

The owner's zero-configuration ruling (2026-09-23): nothing configures
the graph beyond chat models. The prior-knowledge injection — its budget
dial, its runner, its marker part, its dock/dispatch entries — is
removed across all bands; the prober now reads the learner's persistent
knowledge map on demand through two gated tools instead:

- list_sessions: every birth session, names + kinds + counts + dates
  (graphSessionIndex, Platform's core seam)
- list_propositions(session): what was born there + the session's own
  latest understanding level + that evaluation's date
  (graphSessionPropositions) — names/levels/dating ONLY, no statement
  text (owner ruling: the map's organization is the prober's business,
  its prose is not)

Registered via createProberTools when chat-handler passes graphStore
(the graphToolsEnabled gate decided server-side, per-turn fresh); the
prober doctrine gains the map-review nudge at session start.

Also: runner's JobKind special-casing collapses (KIND_ROLE/KIND_RUNNERS
are plain records again), semantic-clusters.ts dies with its test, the
embedder dep's doc tells the wave-7 stub story, and ports.ts's
readClusterLabels/readNamingRuns surface stays untouched for Platform's
ledger-port interlude.

848/848 tests, typecheck/lint/build green.

src/core/ports.ts

@@ -130,11 +130,10 @@ export interface GraphStore {
 
 	/** The embeddings ledger (config.EMBEDDINGS_FILE) — INERT DATA since
 	 *  wave 7 (owner ruling 2026-09-23: the provider embedder is dead;
-	 *  clustering is birth-session, labels are session names). Kept ONLY
-	 *  because the graph-context injection (agent band, Teacher's pass
-	 *  removes it) still reads it for vector-space staleness — the seam
-	 *  dies with it in the follow-up interlude. graph-deletion keeps
-	 *  pruning dead vectors meanwhile (harmless housekeeping). */
+	 *  clustering is birth-session, labels are session names; the
+	 *  graph-context injection is gone with it). The whole seam dies in
+	 *  the follow-up interlude; graph-deletion's vector pruning is
+	 *  harmless housekeeping meanwhile. */
 	readEmbeddings(): EmbeddingsLedger;
 	/** Replace the whole ledger (graph-deletion's vector pruning only). */
 	writeEmbeddings(ledger: EmbeddingsLedger): void;