Wave 7 chunk B: remove the embeddings machinery — the ladder collapses

The owner's wave-7 ruling: embeddings die entirely (git history is the
stash); clustering is birth-session derived (chunk A, 950ddfd), labels
are session names, and the prober's graph tools replace injection.

- settings: GraphSettings collapses to { enabled } — embedding,
  embeddingModel, clustering, labeling all die. Migration story: stale
  record keys are UNREAD and dropped by the sanitizer's reconstruction;
  the next graph-section PUT (replace-whole) persists the collapsed
  shape. The settings-panel GraphSection renders one master row.
- deleted: src/server/embeddings.ts (adapters, resolveEmbeddingPortFor,
  embedNewNodes, embeddingPort, embeddingModelCatalog), the
  GET /api/models/embeddings route, scripts/embed-graph.ts, tests for
  all three, and the /api/models/embeddings picker surfaces in the UI.
- prices: EMBEDDING_PRICES overlay + callCost fallback die. cost-summary:
  the embedding stage fold dies — back to three stages (extraction/
  audit/naming) per the owner ruling; historical stages.embedding spend
  in old run records is simply not displayed.
- ports: EmbeddingPort/EmbeddingResult/EmbeddingTask die. The embeddings
  LEDGER surface (readEmbeddings/writeEmbeddings + EmbeddingsLedger +
  EMBEDDINGS_FILE + graph-deletion's vector pruning) STAYS — inert data,
  kept only so graph-context.ts compiles until Teacher's pass removes
  it; the seam dies in the follow-up interlude.
- chat-handler (approved cross-lane unwiring, wave-6 precedent): the
  extraction pipeline's embedder becomes a documented no-op (nothing
  embedded, nothing spent, ledger untouched) until Teacher's pass
  removes the phase; the graph-context injection dispatch gate, the
  graphContext deps wiring, the setContextRespawn seam, and
  turn-service's triggerGraphContext are gone — injection is dead
  code pending Teacher's file deletions.
- scripts: backfill-graph/import-notes pass the same no-op embedder;
  replay-layout derives clusters from birthSessionPartition (the same
  partition the real settle uses) instead of the embeddings ledger.
- settings-body: parseGraphSettingsBody reads the master switch only —
  old-shape keys in a body are ignored, not rejected; bad shapes 400.
- next.config: the @huggingface tracing-exclusion guards die with the
  last reference.

Cross-lane flags: extraction.ts/graph-context.ts keep stale embed
comments + the embed phase until Teacher's full pass (their parallel
interlude owns those files — zero overlap kept by design);
semantic-clusters.ts + its test stay one more round (extraction.test.ts,
Teacher's file, still imports it — they delete it with the namer cases);
ChatSettings.graphContextTokens + the graph-context-control UI stay
until Teacher+UI.

Gates: tsc clean, eslint clean, 885/885 tests, build compiles.
Live-verified on the port-3004 dev tree: PUT /api/settings/graph with
dead keys collapses on write, bad shapes 400, GET reads {enabled: true},
/api/models/embeddings 404s.

tests/cost-summary.test.ts

@@ -96,39 +96,6 @@ describe("graphCostSummary (the cost pill's fold)", () => {
 		assert.equal(s.unpricedRuns, 1); // run-level: only the both-stages run
 	});
 
-	test("the embedding stage (wave 6): folds when present, absent when the run embedded nothing", () => {
-		const EMBED_MODEL = "openai:text-embedding-3-small";
-		const embStep = callCost(step(5000, 0), EMBED_MODEL)!;
-		assert.ok(embStep > 0, "the overlay prices the known embedding models");
-		const withEmbed = extractionRun(100, PRICED, PRICED);
-		withEmbed.stages.embedding = { model: EMBED_MODEL, steps: [step(5000, 0)] };
-		const s = graphCostSummary({
-			chats: [{ title: "a", extractions: [withEmbed] }, { title: "b", extractions: [extractionRun(200, PRICED, PRICED)] }],
-			sources: [],
-			naming: [],
-		});
-		assert.equal(s.stages.embedding.runs, 1, "only the run that embedded");
-		assert.equal(s.stages.embedding.dollars, embStep);
-		assert.equal(s.stages.embedding.tokens.inputTokens, 5000);
-		assert.equal(s.stages.extraction.runs, 2, "the two-stage era still folds");
-		assert.equal(s.stages.extraction.runs, 2);
-		// Run-level: the embedding dollars ride the run's total.
-		const extStep = callCost(step(1000, 200), PRICED)!;
-		const audStep = callCost(step(2000, 100), PRICED)!;
-		assert.equal(s.runs.find((r) => r.startedAt === 100)!.dollars, extStep + audStep + embStep);
-		assert.equal(s.runs.find((r) => r.startedAt === 200)!.dollars, extStep + audStep);
-		assert.equal(s.totalDollars, (extStep + audStep) * 2 + embStep);
-	});
-
-	test("an UNPRICED embedding model stays honest: counted, never a silent zero; a priced sibling saves the run total", () => {
-		const unpricedEmbed = extractionRun(100, PRICED, "unknown-model");
-		unpricedEmbed.stages.embedding = { model: "some/new-embed", steps: [step(900, 0)] };
-		const s = graphCostSummary({ chats: [{ title: "x", extractions: [unpricedEmbed] }], sources: [], naming: [] });
-		assert.equal(s.stages.embedding.unpricedRuns, 1);
-		assert.equal(s.stages.embedding.dollars, 0);
-		assert.notEqual(s.runs[0]!.dollars, null, "the priced extractor saves the run total");
-	});
-
 	test("recent runs cap: newest survive", () => {
 		const extractions = [1, 2, 3, 4].map((n) => extractionRun(n * 100, PRICED, PRICED));
 		const s = graphCostSummary({