Cost channel cull: the cluster-naming fold dies — two stages, two channels

Off UI's d651f93 flag (displayCostTotals already isolates the display to
extraction + audit; the naming stage row and naming runs were filtered
out client-side). This culls the server side of the same ruling.

THE STANDING RULING, REVERSED BY ITS OWN PREMISE: NamingRunUsage /
readNamingRuns / appendNamingUsage were kept at the wave-7 namer kill
ONLY because cost-summary's HISTORICAL naming stage read them. With the
fold culled, that premise dies — so the whole ledger read path goes too,
following the wave-7 embeddings precedent chain: consumer-less ledger
seams are deleted, and the on-disk naming-runs.jsonl stays INERT (real
trees keep their historical spend bytes; they are simply not displayed
anywhere — the same treatment as historical stages.embedding spend).

- core/cost-summary.ts: two channels in (chat + notes front doors), two
  stages out; RecentRun.kind collapses to "extraction" (labels field
  gone); CostSummaryInput.naming gone; totalDollars = extraction + audit.
- ports/store/contracts/config: appendNamingUsage + readNamingRuns ports,
  store impls + guards, the NamingRunUsage interface, and
  LEDGER_FILES.namingRuns die. graphRevision no longer counts the file
  (a smaller revision value is harmless — reads never compare).
- components/graph-view.tsx (mechanical, flagged): the defensive
  .filter(run.kind !== "naming") guards a kind that no longer exists.
- Tests: cost-summary's both-channels fold pins; the naming fixtures and
  the appendNamingUsage store pin die with the seams.

src/store/graph.ts

@@ -42,7 +42,6 @@ import type {
 	ProvenancePoint,
 	CoverageEntry,
 	SessionCheckpoint,
-	NamingRunUsage,
 } from "../core/contracts.ts";
 import type { GraphStore } from "../core/ports.ts";
 
@@ -89,18 +88,6 @@ function readValid<T>(file: string, isValid: (v: unknown) => v is T): T[] {
 const isProvenancePoint = (v: unknown): v is ProvenancePoint =>
 	isRecord(v) && isString(v.chatId) && isString(v.messageId);
 
-const isNamingStats = (v: unknown): v is NamingRunUsage["stats"] =>
-	isRecord(v) &&
-	["detected", "claimed", "named", "appended"].every((k) => typeof v[k] === "number");
-
-const isNamingRun = (v: unknown): v is NamingRunUsage =>
-	isRecord(v) &&
-	typeof v.startedAt === "number" &&
-	isString(v.at) &&
-	typeof v.durationMs === "number" &&
-	isString(v.model) &&
-	Array.isArray(v.steps) &&
-	isNamingStats(v.stats);
 
 const isGraphNode = (v: unknown): v is GraphNode =>
 	isRecord(v) &&
@@ -190,18 +177,6 @@ export const graphStore: GraphStore = {
 		return readValid(LEDGER_FILES.coverage, isCoverageEntry);
 	},
 
-	// ── cluster-naming run usage (config.LEDGER_FILES.namingRuns) ──
-
-	/** Idempotent per startedAt — the same discipline as every usage
-	 *  channel (chats.appendExtractionUsage, appendSourceUsage). */
-	appendNamingUsage(entry: NamingRunUsage): void {
-		if (this.readNamingRuns().some((r) => r.startedAt === entry.startedAt)) return;
-		appendLine(LEDGER_FILES.namingRuns, entry);
-	},
-	readNamingRuns(): NamingRunUsage[] {
-		return readValid(LEDGER_FILES.namingRuns, isNamingRun);
-	},
-
 	// ── imported-notes bookkeeping (config.SOURCES_FILE — a JSON map) ──
 
 	/** Upsert: keeps the existing record's usage log when re-importing. */