Introduce mypy static type-checking

[apgeorg]

Adds mypy static type-checking to the project and CI.

• New typecheck make target (cd Model && mypy .), folded into make ci.
• Runs in CI between lint and tests.
• Fixes the errors mypy surfaced

Config

Lenient by design so typing can be adopted incrementally:

• ignore_missing_imports — uninstalled optional deps (osmnx, PIL, …) don't fail the build.
• follow_imports = silent — untyped legacy code doesn't block checking.

So mypy only flags real type errors today; stricter per-module rules can be added later.

[riita10069]

One thing I would adjust before merging: the camera_timestamps change seems to weaken an existing invariant. NvidiaAVDataset preloads timestamps for all cameras, but __getitem__ now builds the dict with .get(), and load_camera_frame() accepts np.ndarray | None and falls back to reading the parquet again when a value is missing.

That makes cache misses look like valid fallback behavior, whereas they probably indicate an internal inconsistency. It also risks silently reintroducing per-sample parquet reads.

I’d prefer to keep the stricter invariant:

camera_timestamps = {
    cam_name: self._camera_timestamps[(clip_uuid, cam_name)]
    for cam_name in self.camera_names
}

and keep load_camera_frame(..., camera_timestamps: dict[str, np.ndarray] | None = None) with direct indexing when the cache dict is provided.

[apgeorg]

One thing I would adjust before merging: the camera_timestamps change seems to weaken an existing invariant. NvidiaAVDataset preloads timestamps for all cameras, but __getitem__ now builds the dict with .get(), and load_camera_frame() accepts np.ndarray | None and falls back to reading the parquet again when a value is missing.

That makes cache misses look like valid fallback behavior, whereas they probably indicate an internal inconsistency. It also risks silently reintroducing per-sample parquet reads.

I’d prefer to keep the stricter invariant:

camera_timestamps = {
    cam_name: self._camera_timestamps[(clip_uuid, cam_name)]
    for cam_name in self.camera_names
}

and keep load_camera_frame(..., camera_timestamps: dict[str, np.ndarray] | None = None) with direct indexing when the cache dict is provided.

thank you @riita10069 for your clarification.. reverted!

[riita10069]

Thanks