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.

components/graph-view.tsx

@@ -298,6 +298,8 @@ function fmtRunCost(dollars: number | null): string {
  * titles / file names — so the core's naming fold (and its historical
  * spend) is deliberately not shown anywhere: the pill and the panel must
  * agree, and both read THIS, never GraphCostSummary.totalDollars.
+ * (The core fold's naming stage was then culled outright — 2026-09-24 —
+ * so the recent-runs list carries extraction runs only.)
  */
 export function displayCostTotals(costs: Pick<GraphCostSummary, "stages">): {
 	totalDollars: number;
@@ -393,9 +395,7 @@ function GraphCostPanel({ costs }: { costs: GraphCostSummary }) {
 				))}
 			</div>
 			<div className="mt-2 flex flex-col gap-0.5 border-t pt-2">
-				{costs.runs
-					.filter((run) => run.kind !== "naming")
-					.map((run) => (
+				{costs.runs.map((run) => (
 						<div key={run.startedAt} className="flex items-baseline justify-between gap-2 text-[11px]">
 							<span className="min-w-0 flex-1 truncate text-muted-foreground">
 								<span className="text-foreground/70">{timeAgo(run.startedAt)}</span>{" "}