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/base.py

@@ -0,0 +1,50 @@
+"""Game profiles: everything specific to one engine or one concrete game build.
+
+The shared pipeline (upload, queue, storage, mods, player shell) only talks to
+this interface. A game that needs its own importer, validator or runtime adds a
+profile in ``app/games`` and registers it; nothing else has to change.
+"""
+from __future__ import annotations
+
+from collections.abc import Callable
+from pathlib import Path
+from typing import TYPE_CHECKING, Any
+
+if TYPE_CHECKING:
+    from app.converter.pipeline import Result
+
+Progress = Callable[[str], None]
+
+
+class GameProfile:
+    """Base class. Subclasses override what differs from a plain engine import."""
+
+    #: Stable identifier stored in reports, e.g. ``renpy`` or ``tomie/expansion-1.3801``.
+    id: str = ""
+    #: Engine family from ``compatibility.detect`` this profile applies to.
+    engine: str = ""
+    #: ``game.json`` ``runtime`` value for games played by a dedicated player (None = shared player).
+    runtime: str | None = None
+    #: True for profiles pinned to one concrete build; they win over the engine's generic profile.
+    specific: bool = False
+    #: True when ``pipeline.convert_archive`` itself performs the conversion (Ren'Py).
+    converts_in_pipeline: bool = False
+
+    def claims(self, root: Path) -> bool:
+        """Whether this profile recognises the game at ``root`` (cheap, no media decoding)."""
+        return True
+
+    def inspect(self, root: Path, work: Path | None = None) -> dict[str, Any]:
+        """Read-only compatibility check; raise ``CompatibilityError`` to refuse the game."""
+        raise NotImplementedError
+
+    def convert(self, root: Path, work: Path, progress: Progress) -> Result:
+        """Full import into a PGVN package."""
+        raise NotImplementedError
+
+    def validate_mod(self, game: dict[str, Any], scripts: dict[str, Any], manifest: dict[str, Any]) -> None:
+        """Extra checks for edited mods of games using this profile; raise ``ValueError``."""
+
+    def unity_hooks(self) -> Any | None:
+        """Hooks for the shared Unity/Naninovel reader (see ``app.games.hooks``)."""
+        return None