chore: add CI, lint config, login rate limit and split large modules

- Rate-limit failed logins (8 per 15 min per IP or username, 429 + Retry-After)
- Add ruff/mypy config and GitHub Actions workflow (ruff, pytest, tsc, tests, build)
- Apply ruff autofixes (import order, pyupgrade)
- Extract rpy_helpers.py, engine-util.ts, TranslationParts.tsx and
  translation-types.ts from oversized modules
- Add dependency-free React UI tests
- Refresh README and ARCHITECTURE (Naninovel/Tomie, status and plans)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

backend/app/routers/versions.py

@@ -1,19 +1,26 @@
-from typing import Annotated, Any
 import asyncio
+from typing import Annotated, Any
 
 from fastapi import APIRouter, Depends, HTTPException, Request, status
 from sqlalchemy import select
 from starlette.concurrency import run_in_threadpool
 from starlette.requests import ClientDisconnect
 
+from app import translation
 from app.deps import DB, CurrentUser, has_perm, require
 from app.models import Game, GameVersion, Revision, Save, User, VersionHistory
 from app.routers.games import get_game
 from app.schemas import (
-    ForkIn, HistoryOut, PublishIn, SaveDetailOut, SaveIn, SaveOut, VersionDetailOut, VersionIn,
+    ForkIn,
+    HistoryOut,
+    PublishIn,
+    SaveDetailOut,
+    SaveIn,
+    SaveOut,
+    VersionDetailOut,
+    VersionIn,
     VersionOut,
 )
-from app import translation
 from app.uploads import remove_upload, upload_path
 
 router = APIRouter(prefix="/api", tags=["versions"])
@@ -79,9 +86,9 @@ async def upload_version(
         await db.commit()
         raise HTTPException(status.HTTP_400_BAD_REQUEST, "Пустой файл")
 
-    from app.converter.preflight import probe_archive
     from app.converter.archive import ArchiveError
     from app.converter.compatibility import CompatibilityError
+    from app.converter.preflight import probe_archive
     try:
         probe = await asyncio.to_thread(probe_archive, path, filename)
     except (CompatibilityError, ArchiveError, OSError, ValueError) as exc: