feat(rules): show what an apply run changed, and which rule ran

Apply History listed only counts - '13 matches · 13 transactions' - which reads
identically whether the run renamed a merchant or split every transaction with
another participant. Revert is destructive, so that is not enough to decide on.

Two additions. Migration 0017 records rule_id, rule_name and source on each run:
rule_name is denormalised so history stays readable after a rule is edited or
deleted, and there is no FK so deleting a rule cannot cascade away the audit
trail. Both write paths now populate it - the condition-matched run and the
selection-based quick action.

And rows expand to show the run's snapshot set against current values: which
transactions were touched and what changed on each. Rows changed by something
else since the run are called out, because reverting restores the pre-run value
and would discard that later edit.

Runs recorded before this show 'Unknown rule' - the rule they came from is not
recoverable.

src/lib/hooks.ts

@@ -617,6 +617,38 @@ export interface RuleRun {
   matched: number;
   transactions_affected: number;
   reverted_at: string | null;
+  // Provenance (migration 0017). NULL on runs recorded before it existed.
+  rule_id: number | null;
+  rule_name: string | null;
+  source: "all" | "rule" | "selection" | null;
+}
+
+export interface RuleRunDetail {
+  run: RuleRun & { transactions_affected: number };
+  transactions: {
+    id: number;
+    transaction_date: string;
+    description: string;
+    amount: number;
+    amount_aud: number | null;
+    bank_name: string;
+    merchant: string | null;
+    changes: { field: string; from: string | null; to: string | null }[];
+  }[];
+  still_changed: number;
+}
+
+/** What a run actually did — loaded on demand when a row is expanded. */
+export function useRuleRunDetail(runId: number | null) {
+  return useQuery<RuleRunDetail>({
+    queryKey: ["rule-run-detail", runId],
+    enabled: runId != null,
+    queryFn: async () => {
+      const res = await fetch(`/api/rules/runs/${runId}`);
+      if (!res.ok) throw new Error("Failed to load run detail");
+      return res.json();
+    },
+  });
 }
 
 export function useRuleRuns() {