refactor: move game-specific import logic into profiles; unblock Tomie import

- Add app/games: GameProfile base, registry, ReaderHooks and renpy/naninovel/
  tomie profiles. pipeline, preflight, detect and mods dispatch via the registry
- Move tomie_* converter modules to app/games/tomie and split out reader hooks,
  import, mod validation and known defects
- Tolerate the 31 authoring defects of the pinned Tomie build as report
  warnings (exact list, per-script counts); any new defect still blocks import
- Frontend: runtime registry (runtimes.ts) with lazy Tomie launcher
- Add profile/registry tests and docs/GAME_PROFILES.md; update IMPORT.md

Full media export of the original Tomie build is not yet verified.

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

backend/app/games/naninovel.py

@@ -0,0 +1,19 @@
+"""Generic Naninovel games: compiled scripts become ordinary PGVN modules."""
+from pathlib import Path
+
+from app.games.base import GameProfile, Progress
+
+
+class NaninovelProfile(GameProfile):
+    id = "naninovel"
+    engine = "naninovel"
+
+    def inspect(self, root: Path, work: Path | None = None) -> dict:
+        from app.converter.naninovel import inspect_naninovel
+
+        return inspect_naninovel(root, work=work)
+
+    def convert(self, root: Path, work: Path, progress: Progress):
+        from app.converter.naninovel import convert_naninovel
+
+        return convert_naninovel(root, work, progress)