feat(planning): make optimization rules composable

Evaluate explicit, ordered optimization configurations through one shared
planner model. Add six editable presets, durable one-time legacy migration,
and consistent completed and cancelled plan provenance.

Include functional regressions and the agreed trace-removal and benchmark
follow-up specs. Performance acceptance remains in #78 under unchanged gates.

Refs: #70, #71, #72, #73, #74, #75, #76, #77, #78

docs/adr/0008-user-controlled-planning-objectives.md

@@ -20,4 +20,6 @@ After all active rules compare equally, earlier balance expiry and then earlier
 
 Only active rules drive placement decisions and preference comparisons; disabled or deleted optimization rules have no residual influence through fixed optimization stages or protected metrics. With no active rules, the planner adds no leave placements, even when balances are at risk of expiring, and retains declared non-working days. Final tie-breakers cannot independently trigger new placements.
 
-Implementation is pending.
+Implemented in the #70–#75 series. Saved-rule migration and functional verification
+are covered by #75. Benchmark performance acceptance and any required optimization
+are tracked separately in #78; the benchmark limits remain unchanged.