PC controls: keyboard pan/zoom, Tab cycle, Escape stack, right-click deselect

Adds full PC keyboard+mouse support on top of existing touch controls. Touch
paths untouched. All input goes through named actions in project.godot.

Bindings:
- WASD / arrows: camera pan (speed scales with zoom)
- = / -: keyboard zoom in/out
- C / Home: center on selected pawn
- Tab / Shift+Tab: cycle through pawns (pans camera to selection)
- B / L / P / ,: toggle BuildDrawer / AlertsLog / WorkPriorityMatrix / Settings
- Escape: cancel active designation tool > close topmost panel > deselect pawn
- Right-click: cancel active tool or deselect pawn (RTS convention)
- F: speed_cycle (action restored; handler still TODO)
- pawn_prev action removed; Shift+Tab read via event.shift_pressed inline

Escape priority enforced by Designation._input running before _unhandled_input
plus each panel consuming its own cancel action when visible.

Also fixes a pre-existing pre-Phase-17 bug: WorkPriorityMatrix, AlertsLog,
StorytellerModal, LoadMenu, and SettingsMenu had MOUSE_FILTER_STOP Controls
(Backdrop / Dim) that remained input-active when the panel was "closed" —
their open/close paths only toggled _root.visible / _panel.visible, never
CanvasLayer.visible. World mouse events (right-click deselect, left-click
pawn-select) were silently eaten. Now each _set_visible / open / close
toggles self.visible (the CanvasLayer) so input dispatch shuts off properly.

Verified end-to-end via MCP runtime: WASD pan, zoom keys, Tab+Shift+Tab
cycle, B-open + Escape-close, right-click deselect, left-click pawn-select
all working in sequence with no input bleed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scenes/world/world.gd

@@ -122,6 +122,12 @@ func _ready() -> void:
 	pathfinder.setup(MAP_SIZE_TILES)
 	_wire_walls_to_pathfinder()
 	selection.bind(pathfinder)
+	# Bind the camera so Tab-cycle and center-on-selection can pan to pawns.
+	var camera_rig := get_node_or_null("CameraRig")
+	if camera_rig != null:
+		selection.bind_camera(camera_rig)
+	else:
+		Audit.log("world", "selection.bind_camera: CameraRig not found")
 	World.pathfinder = pathfinder  # expose to entities (Tree.fell() walkability checks, etc.)
 
 	# Phase 5 — expose TileMap layer refs on the autoload so entity code