fix(client): address PR #36 re-review — 7 items from Hoshe + Tyre

Warnings: facing indicator tests use Godot-normalized rotation range
(-PI, PI] instead of raw addition (SW/W/NW in test_rendering,
West in test_client_p3). Suggestions: cache font in world_radial
_draw(), fix docstring on deactivate_insert() trigger, document
tile-coordinate system on _eval_player_near (D-066), add public
reset_facing_state() to InputMapper (D-030 testability).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/tests/test_input_mapper_facing.gd

@@ -116,7 +116,4 @@ func test_wasd_strafe_right_facing_west() -> void:
 
 
 func after_test() -> void:
-	# Reset facing to default
-	InputMapper.facing_angle = -PI / 2.0
-	InputMapper.facing_octant = "North"
-	InputMapper._last_sent_octant = "North"
+	InputMapper.reset_facing_state()