upgrade: adopt V8.21.3 (V8.13→8.21.3: P5 SFTP/S3, P6 multilingual, editor overhaul, enterprise hardening)

Overlay ~150 upstream items onto our V8.12 base, preserving trade-pro
theme, registry tests, and design docs. Re-applied our patch set
(discovery/env_for/blocks.css/type-mapping/theme_color/frontend entries,
test_theme_pro_v3 mods) — all anchors survived upstream evolution.

New platform enhancement (fixes upgrade-introduced regression):
multilingual.site_locale now honors settings_json.locale, plus
PUT /api/i18n/sites/{id}/locale — standalone English sites get
<html lang='en'> under the V8.15 locale-rewrite pipeline.

compose: adopt V8.21.3 (image 8.21.3-dev.1, /api/ready probes, MySQL/S3
env) with project name pinned to siteforge-v8-10 (data volumes).

Tests: 356 passed / 11 failed — all 11 confirmed pre-existing in
pristine V8.21.3 on this host (10 upstream Windows env + our build test
now green after locale fix). Patch registry updated in plan doc.

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

app/factory_api.py

@@ -1,5 +1,6 @@
 """Factory V2 endpoints: themes, mappings, build comparisons, team release readiness."""
 import json,csv,io
+from typing import Any
 from pathlib import Path
 from fastapi import APIRouter, HTTPException, Request, UploadFile, File, Body
 from fastapi.responses import HTMLResponse, FileResponse
@@ -88,10 +89,11 @@ def save_profile(request:Request,site_id:str,payload:dict=Body(...)):
 
 class MapRows(BaseModel):
     rows:list[dict]=Field(max_length=1000)
-    rules:dict[str,str]=Field(default_factory=dict)
+    rules:dict[str,Any]=Field(default_factory=dict)
     content_type:str='product'
     prefix:str|None=None
     on_conflict:str='skip'
+    expected_plan_hash:str|None=None
     dry_run:bool=True
 
 @router.post('/sites/{site_id}/mapping/parse-file')
@@ -115,7 +117,7 @@ def suggested_map(request:Request,site_id:str,payload:dict=Body(...)):
 def map_rows(request:Request,site_id:str,payload:MapRows):
     enterprise.require(request,site_id,'viewer' if payload.dry_run else 'editor')
     try:
-        return assembly.dry_run(site_id,payload.rows,payload.rules,payload.content_type,payload.prefix) if payload.dry_run else assembly.commit(site_id,payload.rows,payload.rules,payload.content_type,payload.on_conflict,payload.prefix)
+        return assembly.dry_run(site_id,payload.rows,payload.rules,payload.content_type,payload.prefix) if payload.dry_run else assembly.commit(site_id,payload.rows,payload.rules,payload.content_type,payload.on_conflict,payload.prefix,payload.expected_plan_hash)
     except ValueError as exc:raise HTTPException(400,str(exc))
 
 @router.get('/sites/{site_id}/migration/readiness')