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/ui-message.ts

@@ -1,7 +1,6 @@
 import type { UIMessage } from "ai";
 import type {
 	DemoToolInput,
-	GraphContextData,
 	PdfToolInput,
 	PlanVerdictData,
 	PlanBlockData,
@@ -68,10 +67,6 @@ export type TeacherUIDataParts = {
 	/** The probe→teach handoff wake: the wake pipeline's steer message,
 	 *  carrying ONLY this part (the model-facing text lives in the adapter). */
 	"probe-handoff": { chatId: string };
-	/** The prior-knowledge injection's delivery (vision-context-injection.md):
-	 *  the marker-only steer — the counts for the UI, the full block content
-	 *  for the audit trail; the adapter flattens it to graphContextText. */
-	"graph-context": GraphContextData;
 	/** The abort steer's message-type marker (the abort badge renders off it). */
 	"subagent-aborted": SubagentResultMeta & { aborted: true };
 };