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>

reports/v826/summary.json

@@ -0,0 +1,12 @@
+{
+  "version": "8.26.0-dev.1",
+  "python_tests_passed": 376,
+  "python_batches_passed": 23,
+  "python_batches_failed": 0,
+  "javascript_tests_passed": 13,
+  "http_worker_e2e": "passed",
+  "isolated_chromium_demo": "passed_with_set_content",
+  "real_logged_in_browser": "not_verified",
+  "production_pg_redis_docker": "not_verified",
+  "official_art_build": "not_verified"
+}