remove Python stopgap; rewire to pql 1.0

pql 1.0 ships full feature parity for decisions and tickets.
Sunset condition from D-040 met; deletion per R-011.

Removed: tools/scripts/plan entrypoint, tools/scripts/planning/
Python modules, tools/scripts/README.md, .gitignore pycache
entries.

Rewired: make decisions-validate now calls pql decisions validate.
CLAUDE.md decision discipline guardrail points at pql. Extension
stub comments updated. decisions/README.md examples use pql.
D-040 amended as superseded.

Co-Authored-By: Claude <noreply@anthropic.com>

app/lib/builtin/decisions/src/extension.dart

@@ -2,9 +2,7 @@ import 'package:clide_app/extension/extension.dart';
 
 /// Tier-reserved stub. Will surface a sidebar tab (filter by domain /
 /// status, backlinks from current file) + commands (`decisions.open`,
-/// `decisions.claim`, `decisions.amend`). Data source: `pql decisions
-/// …` once `Q-021` resolves; `tools/scripts/plan decisions …` until
-/// then.
+/// `decisions.claim`, `decisions.amend`). Data source: `pql decisions …`.
 class DecisionsExtension extends ClideExtension {
   @override
   String get id => 'builtin.decisions';

app/lib/builtin/tickets/src/extension.dart

@@ -2,9 +2,8 @@ import 'package:clide_app/extension/extension.dart';
 
 /// Tier-reserved stub. Will surface a sidebar tab (filtered list) + a
 /// workspace tab (kanban board) + commands (`tickets.open`,
-/// `tickets.new`, `tickets.move`, `tickets.block`). Data source: `pql
-/// ticket …` once `Q-021` resolves; `tools/scripts/plan ticket …` until
-/// then. Ticket persistence strategy open at `Q-022`.
+/// `tickets.new`, `tickets.move`, `tickets.block`). Data source:
+/// `pql ticket …`. Ticket persistence strategy open at `Q-022`.
 class TicketsExtension extends ClideExtension {
   @override
   String get id => 'builtin.tickets';