chore(linter): ensure motors module passes MyPy type checks (#2939)

* fix: ensure motors module passes MyPy type checks

This commit fixes 62 mypy type errors in the motors module by:

- Updating Protocol classes (PortHandler, PacketHandler, GroupSyncRead,
  GroupSyncWrite) to use class-level attribute declarations instead of
  __init__ body declarations
- Adding missing `broadcastPing` method to PacketHandler Protocol
- Fixing return type annotations (e.g., `_get_motor_model` returns str, not int)
- Fixing parameter types to use `Sequence` for covariant list parameters
- Fixing `Mapping` for covariant dict value types in `_normalize`
- Updating method signatures to be consistent across parent and child classes
  (disable_torque, enable_torque, _get_half_turn_homings)
- Adding explicit `int()` casts for MotorCalibration arguments
- Adding explicit `return None` for functions returning Optional types
- Adding type annotations for variables like `data_list: dict[int, int]`
- Using `# type: ignore[method-assign]` for intentional monkeypatch
- Fixing variable references (using `self.groups` instead of `groups`)

Fixes #1723

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* chore(style): pre-commit after main merge

* chore(linter): solve comments

* chore(linter): apply pre-commit fixes to damiao

* chore(linter): more fixes to damiao

---------

Co-authored-by: yurekami <yurekami@users.noreply.github.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

pyproject.toml

@@ -360,9 +360,9 @@ ignore_errors = false
 module = "lerobot.cameras.*"
 ignore_errors = false
 
-# [[tool.mypy.overrides]]
-# module = "lerobot.motors.*"
-# ignore_errors = false
+[[tool.mypy.overrides]]
+module = "lerobot.motors.*"
+ignore_errors = false
 
 # [[tool.mypy.overrides]]
 # module = "lerobot.robots.*"