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/server/graph.ts

@@ -42,14 +42,14 @@ export function graphCosts(): GraphCostSummary {
 		.readSources()
 		.filter((s) => s.extractions?.length)
 		.map((s) => ({ filePath: s.filePath, extractions: s.extractions! }));
-	return graphCostSummary({ chats, sources, naming: stores.graphStore.readNamingRuns() });
+	return graphCostSummary({ chats, sources });
 }
 
 /** The graph's version stamp (session-deletion wave 6): the max mtime
- *  across every graph data file — ledgers, positions, embeddings. Moves
- *  on ANY graph write (merge append, settle, embed, or a deletion's
- *  atomic rewrite), never moves on reads, and needs no bookkeeping of
- *  its own: the fs IS the counter. Consumers poll it (the activity feed
+ * across every graph data file — ledgers, positions. Moves on ANY
+ * graph write (merge append, settle, or a deletion's atomic rewrite),
+ * never moves on reads, and needs no bookkeeping of its own: the fs
+ * IS the counter. Consumers poll it (the activity feed
  *  carries it; the DELETE response returns it) to know clusters/layout
  *  must refetch — the "graph changed underneath me" signal. */
 export function graphRevision(): number {
@@ -61,7 +61,6 @@ export function graphRevision(): number {
 		LEDGER_FILES.mappings,
 		LEDGER_FILES.sessions,
 		LEDGER_FILES.coverage,
-		LEDGER_FILES.namingRuns,
 		POSITIONS_FILE,
 	]) {
 		try {