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/clusters.ts

@@ -1,9 +1,8 @@
 /**
- * CLUSTER LABEL MATCHING (vision §1). DETECTION moved to semantic topic
- * clustering over embeddings (core/semantic-clusters.ts, DECIDED
- * 2026-09-13) — Louvain over the edge structure is retired: it only ever
- * found the reasoning chains (the graph is disconnected by nature), and
- * edge-orphans could never join anything. What REMAINS here is the
+ * CLUSTER LABEL MATCHING (vision §1). DETECTION is birth-session
+ * clustering since wave 7 (core/session-clusters.ts; the semantic
+ * embedder and its Louvain predecessor are both dead). What REMAINS here
+ * is the
  * cluster contract + core-survival label matching, which is
  * detection-agnostic: it consumes the same { members } shape semantic
  * clustering emits.