feat(P1): restore S&P Global Energy theme + PPTX automation (REQ-214, REQ-228)

REQ-214: Restore the S&P Global Energy Marp style: block (from commit
ae0cb58 / v1.9.2 P45) to the unified deck. Colors: H1/H2 #D6002A (red-core),
title-slide bg #1B1B1B (grey-90) + 8px #D6002A top accent, body #1B1B1B,
blockquote border #D6002A, table headers #F0F0F0, font 'Akkurat Pro' with
web-safe fallbacks. Nova header/footer text preserved (rebrand not touched).
HTML re-rendered (229 S&P color refs confirmed).

REQ-228: scripts/render_deck.sh (HTML + PPTX render + git add) +
scripts/attach_release_asset.py (Gitea release asset upload via API). PPTX
is now a first-class committed binary (D-141, no LFS). README updated:
'PPTX not committed' → 'PPTX committed + attached'. PPTX committed (3.6 MiB,
19 slides).

---ci---
project: acdl
phase: 1
milestone: v1.18
status: execute
requirements:
  covered: [REQ-214, REQ-228]
  partial: []
---/ci---

.ciagent/CHECKPOINT.json

@@ -1,10 +1,12 @@
 {
   "phase": 0,
-  "stage": "plan",
+  "stage": "complete",
   "milestone": "v1.18",
   "phase_role": "pre_execution",
   "attempts": 0,
-  "updated_at": "2026-08-06T00:25:00Z",
+  "updated_at": "2026-08-06T00:35:00Z",
   "milestone_complete": false,
-  "notes": "v1.18 PLAN complete. 8 phases, 6 waves, 15 requirements. Sequential execution."
+  "tag": "v1.17.0",
+  "release_id": 522,
+  "notes": "v1.18 P0 complete. 5 pre-execution stages done. Tag v1.17.0, release 522."
 }