feat(rules): manual-only rules as one-click quick actions on selected transactions

A rule flagged manual_only never runs in the apply-all pass; instead it shows
as a button in the transactions bulk bar and applies its actions to the current
selection (conditions ignored — the selection is the condition). Recorded as a
rule_apply_run, so it reverts from Rules -> Apply History like any other run.

Motivation: tagging Home + splitting 50/50 with Sonu was two bulk actions every
time. Now it is one click, and any other combo can be defined the same way.

Extracts the action-application and snapshot logic from the apply route into
src/lib/rule-actions.ts so both callers share one implementation — splits upsert
rather than delete+reinsert, so settled flags survive.

prisma/migrations/0012_manual_only_rules/migration.sql

@@ -0,0 +1,10 @@
+-- Manual-only rules ("quick actions"): a rule flagged manual_only is never
+-- picked up by the bulk apply-all run. It exists to be fired by hand against a
+-- selection of transactions from the transactions page, so its conditions are
+-- irrelevant — the selection is the condition.
+
+ALTER TABLE rules
+  ADD COLUMN IF NOT EXISTS manual_only BOOLEAN NOT NULL DEFAULT false;
+
+CREATE INDEX IF NOT EXISTS idx_rules_manual_only
+  ON rules (owner_id, manual_only) WHERE manual_only = true;