docs(P3): marp deck + talking points + README + theme CSS + tests (REQ-245,251,252)

Marp deck (nova-autonomous-cloud-delivery-marp.md): synthesize from updated
source-of-truth; 18 main + 1 appendix slides; frontmatter — title 'Nova —
The Autonomous Cloud Delivery Platform', footer without version + without
'Act %{page}/5', title-slide subtitle 'Product Development & Citizen
Developer Overview'; no badges; embedded PNGs.

Talking points (nova-autonomous-cloud-delivery-talking-points.md):
re-distilled to 18-slide + A1 structure.

README.md: update deck title, audience, slide count (18 main + 1 appendix),
directory layout, remove badge docs, update deck table + render commands +
filenames. Document the v1.21 rename + restructure.

Theme CSS (nova-sp-theme.css): fix Appendix A1 table readability — tables
now have explicit white body + black text on any slide background
(including dark/title slides). Item 32.

Tests (test_slides_pipeline.py): add v1.21 assertions — no badges; no
version in footer/title slide; 18 main + 1 appendix slides; no D-###/REQ-
###/.py paths in audience-facing Marp deck or source slide body; old deck
files removed; render script default renamed; README references new deck
name. Update deck path in test_regression_cap023_024.py +
core/regression_verify.py CAP-024 (filename + 18-19 slide range, drop 'Arc
Preview' check per item 3).

attach_release_asset.py: usage example filename updated.

---ci---
project: acdl
phase: 3
milestone: v1.21
status: execute
phase_role: execution
---/ci---

core/regression_verify.py

@@ -593,32 +593,30 @@ def _check_cap_023_metrics_collector() -> Tuple[Status, str]:
 
 
 def _check_cap_024_deck_structure() -> Tuple[Status, str]:
-    """CAP-024: unified deck structure (v1.17).
+    """CAP-024: unified deck structure (v1.17 + v1.21 refinement).
 
-    Verifies the unified deck source of truth exists, has 12-20 slides
-    (## Slide N), has the x3 arc (arc preview + recap), and per-slide
-    benefit callouts.
+    Verifies the unified deck source of truth exists, has 18 main slides
+    (## Slide N) + 1 appendix, has the recap+ask closing, and per-slide
+    benefit callouts. v1.21 renamed the deck + restructured to a 4-beat arc.
     """
     import os
     deck_path = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
-                              "docs", "presentations", "nova-no-humans-platform.md")
+                              "docs", "presentations", "nova-autonomous-cloud-delivery.md")
     if not os.path.isfile(deck_path):
         return "Skipped", "unified deck not found"
     with open(deck_path) as f:
         content = f.read()
     slide_count = content.count("## Slide ")
-    if slide_count < 12 or slide_count > 20:
-        return "Broken", f"deck has {slide_count} slides (expected 12-20)"
-    has_arc_preview = "Arc Preview" in content
+    if slide_count < 18 or slide_count > 19:
+        return "Broken", f"deck has {slide_count} main slides (expected 18-19)"
     has_recap = "Recap + Ask" in content
     has_benefit = content.count("Benefit:") >= 10
-    if not (has_arc_preview and has_recap and has_benefit):
+    if not (has_recap and has_benefit):
         missing = []
-        if not has_arc_preview: missing.append("arc preview")
         if not has_recap: missing.append("recap+ask")
         if not has_benefit: missing.append("per-slide benefit callouts")
         return "Broken", f"deck missing: {missing}"
-    return "Verified", f"deck has {slide_count} slides, x3 arc present, per-slide benefits present"
+    return "Verified", f"deck has {slide_count} slides, recap+ask present, per-slide benefits present"
 
 
 # Registry: ordered, each entry is (capability_id, name, tier, check_fn).