Character and movement pass

NPC characters
- Articulated rig (hips/knees, shoulders/elbows/hands) replaces rigid capsules;
  the walk cycle bends knees and elbows and flees with a longer stride.
- Layered outfits (jacket/vest/coat/dress), extended accessories and hand items
  (bag, umbrella, phone, camera, clipboard, cup), face details and five hair
  silhouettes, all deterministic per profile seed.
- Idle behaviour layers (phone, clipboard, crossed arms, look-around), breathing
  and weight shift; escalation raises hands or points, and noticed NPCs turn
  toward the guard.
- Reaction symbols above the head (!!, ?!, !, ?), door-queue offsets assigned by
  GameManager, three LOD tiers with hysteresis and a billboard impostor.
- smoke_npc_budget.gd: 16 avatars = 534 meshes, ~6.9 ms average (50 ms budget).

Player movement
- Separate accel/decel, step-up assist for kerbs and the entrance steps, and a
  forward-axis fix: W was inverted (get_axis(forward, back) is negative).
- Head bob, landing dip and precision-walk FOV, gated by persisted head-bob and
  invert-Y settings; precision chip and tick; surface-aware footsteps and a
  landing cue forwarded to AudioFeedback.
- Gamepad support (sticks, deadzone, face buttons, bumpers), a control legend
  that follows the active device, and named actions for the remaining keys.
- Key/button remapping in Settings, persisted as input_bindings and applied by
  InputBindings (mouse and gamepad axes are never removed).
- smoke_movement.gd (windowed): climbs the steps, checks precision speed, chip,
  footsteps and landing; new 11-precision-walk capture and catalogue entry.

Verification: headless 208/208, Python tooling 56/56, all 11 smokes pass,
compare 11 good / 0 bad, movement judge match. Version 0.5.0. Only optional
Future ideas remain in TODO.

src/core/input_bindings.gd

@@ -0,0 +1,67 @@
+class_name InputBindings
+extends RefCounted
+## Key/button remaps persisted through the settings panel. Games keep working
+## with the defaults in `project.godot`; only actions the player rebinds are
+## rewritten, and remaps never remove mouse or gamepad axis events.
+
+const REMAPPABLE := [
+	"move_forward", "move_back", "move_left", "move_right",
+	"walk_slow", "inspect", "wand", "radio_emergency", "action_menu",
+]
+
+## Turn an input event into a storable descriptor, or {} when it is not a key or
+## pad button (mouse buttons and axes are deliberately not remappable here).
+static func descriptor_from_event(event: InputEvent) -> Dictionary:
+	if event is InputEventKey:
+		var key := event as InputEventKey
+		var code := key.physical_keycode if key.physical_keycode != 0 else key.keycode
+		if code == 0:
+			return {}
+		return {"type": "key", "code": int(code)}
+	if event is InputEventJoypadButton:
+		return {"type": "joy", "button": int((event as InputEventJoypadButton).button_index)}
+	return {}
+
+static func label_for(descriptor: Dictionary) -> String:
+	match str(descriptor.get("type", "")):
+		"key":
+			return OS.get_keycode_string(int(descriptor.get("code", 0)))
+		"joy":
+			return "Pad %d" % int(descriptor.get("button", 0))
+		_:
+			return ""
+
+## First key/button currently bound to the action, used to label the UI.
+static func current_descriptor(action: String) -> Dictionary:
+	if not InputMap.has_action(action):
+		return {}
+	for event in InputMap.action_get_events(action):
+		var descriptor := descriptor_from_event(event)
+		if not descriptor.is_empty():
+			return descriptor
+	return {}
+
+## Rewrite the actions present in `bindings`. Existing key/button events for
+## those actions are replaced; mouse and joypad-axis events are left alone.
+static func apply(bindings: Dictionary) -> void:
+	for action in bindings.keys():
+		if not InputMap.has_action(action):
+			continue
+		var descriptor: Dictionary = bindings[action]
+		if descriptor.is_empty():
+			continue
+		for event in InputMap.action_get_events(action):
+			if event is InputEventKey or event is InputEventJoypadButton:
+				InputMap.action_erase_event(action, event)
+		InputMap.action_add_event(action, event_for(descriptor))
+
+static func event_for(descriptor: Dictionary) -> InputEvent:
+	match str(descriptor.get("type", "")):
+		"joy":
+			var button := InputEventJoypadButton.new()
+			button.button_index = int(descriptor.get("button", 0))
+			return button
+		_:
+			var key := InputEventKey.new()
+			key.physical_keycode = int(descriptor.get("code", 0))
+			return key