feat(movement): add movement state machine with air/ground/wallrun/slide/dash/ground states

- MovementStateMachine: core state machine base
- MovementParams: export-rich tunable resource
- StateGround/StateAir: grounded & aeriel locomotion with coyote, buffered jump, bunny hop
- StateWallRun / StateWallCling: wall-based traversal with wall-jump off
- StateSlide: sprint-parallel slide with friction fallout
- StateDash: burst dash with momentum brake
- PlayerMovementController: entry point wiring to CharacterBody3D
- input_map.cfg: full action map reference file
- characters/player/player_base.tscn: placeholder scene
- movement/tests/test_fsm_runner.gd: 9-state unit test runner

Closes #1

input_map.cfg

@@ -0,0 +1,114 @@
+; Papaya-Shooter Input Map
+; Copy these into Project Settings > Input Map manually or load at runtime.
+
+[jump]
+type=physical
+deadzone=0.0
+events/0=Key(Space)
+
+[sprint]
+type=physical
+deadzone=0.0
+events/0=Key(Shift)
+
+[crouch]
+type=physical
+deadzone=0.0
+events/0=Key(Control)
+
+[dash]
+type=physical
+deadzone=0.0
+events/0=Key(Shift, pressed=false, double_click=true) ; optional double-tap
+events/1=Key(LShift)
+
+[fire]
+type=physical
+deadzone=0.0
+events/0=MouseButton(button_index=1) ; right click
+events/1=Key(F)
+
+[fire_alt]
+type=physical
+deadzone=0.0
+events/0=MouseButton(button_index=0) ; left click
+
+[reload]
+type=physical
+deadzone=0.0
+events/0=Key(R)
+
+[weapon_1]
+type=physical
+deadzone=0.0
+events/0=Key(1)
+
+[weapon_2]
+type=physical
+deadzone=0.0
+events/0=Key(2)
+
+[weapon_3]
+type=physical
+deadzone=0.0
+events/0=Key(3)
+
+[weapon_4]
+type=physical
+deadzone=0.0
+events/0=Key(4)
+
+[weapon_next]
+type=physical
+deadzone=0.0
+events/0=MouseWheel(direction=1)
+
+[weapon_prev]
+type=physical
+deadzone=0.0
+events/0=MouseWheel(direction=-1)
+
+[move_forward]
+type=physical
+deadzone=0.0
+events/0=Key(W)
+
+[move_back]
+type=physical
+deadzone=0.0
+events/0=Key(S)
+
+[move_left]
+type=physical
+deadzone=0.0
+events/0=Key(A)
+
+[move_right]
+type=physical
+deadzone=0.0
+events/0=Key(D)
+
+[look_x]
+type=axis
+deadzone=0.0
+events/0=MouseMotion(axis=1, position=1) ; horizontal mouse
+
+[look_y]
+type=axis
+deadzone=0.0
+events/0=MouseMotion(axis=1, position=-1) ; vertical mouse (inverted)
+
+[reload]
+type=physical
+deadzone=0.0
+events/0=Key(R)
+
+[interact]
+type=physical
+deadzone=0.0
+events/0=Key(E)
+
+[jump]
+type=physical
+deadzone=0.0
+events/0=Key(Space)