upgrade: adopt V8.32.0-dev.1 (theme preview iframe fix, editor simple mode)

Overlay 46 upstream items; full patch set re-applied (all patched files
reset by overlay regardless of upstream change status — lesson recorded).
Verified: theme suites 35/35; dual-baseline 418 passed vs pristine
389+29 ours, FAILED-set diff EMPTY (same 10 Windows env fails).
Live: container 8.32.0-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=='8.31.0-dev.1'
+assert VERSION=='8.32.0-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