upgrade: adopt V8.31.1 (theme 1.3/1.4 redesigns, editor deep-canvas, guided launch, component library)

Overlay 190 upstream items (V8.22→8.31) preserving trade-pro theme,
registry tests, and design docs. Re-applied full patch set on identical
anchors (discovery/env_for/blocks.css/type-mapping/locale-override/
theme_color/frontend entries/test_theme_pro_v3 mods) plus compose pins.

Verified: theme suites 35/35; dual-baseline full run 415 passed vs
pristine 386+29 ours, FAILED-set diff EMPTY (same 10 Windows env fails).
Live: container 8.31.1-dev.1 healthy, hesupipe 192 entries intact,
trade-pro build 203 pages 0 errors.

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

scripts/verify_release.py

@@ -6,7 +6,7 @@ import sys
 ROOT=Path(__file__).resolve().parent.parent
 sys.path.insert(0,str(ROOT))
 from app.version import VERSION
-assert VERSION=='8.21.3-dev.1'
+assert VERSION=='8.31.0-dev.1'
 api=(ROOT/'app'/'main.py').read_text(encoding='utf-8')
 assert 'return builder.build(' not in api, 'A synchronous request-thread build has reappeared'
 assert "@app.post('/api/sites/{site_id}/builds', status_code=202)" in api