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/ui/work_priority_matrix.gd

@@ -69,6 +69,11 @@ var _cells: Array = []
 func _ready() -> void:
 	layer = 17
 	_build_ui()
+	# Hide the whole CanvasLayer when closed so the Backdrop ColorRect (which
+	# has MOUSE_FILTER_STOP for click-outside-to-close) does not eat mouse
+	# events in `_unhandled_input` for the world below. Toggling _root.visible
+	# alone leaves the Backdrop alive and intercepting clicks.
+	visible = false
 	_root.visible = false
 	Audit.log("work_priority_ui", "WorkPriorityMatrix ready")
 
@@ -78,12 +83,14 @@ func _ready() -> void:
 ## Open the matrix panel and rebuild the grid from current pawn state.
 func open() -> void:
 	_rebuild_grid()
+	visible = true
 	_root.visible = true
 	Audit.log("work_priority_ui", "opened (pawns=%d)" % World.pawns.size())
 
 
 ## Close the panel.
 func close() -> void:
+	visible = false
 	_root.visible = false
 	Audit.log("work_priority_ui", "closed")
 
@@ -222,6 +229,22 @@ func _on_cell_pressed(pawn, category: StringName, btn: Button) -> void:
 	Audit.log("work_priority_ui", "%s: %s → %d" % [pawn.pawn_name, String(category), next])
 
 
+func _unhandled_input(event: InputEvent) -> void:
+	# P — toggle the work priority matrix.
+	if event.is_action_pressed("open_priorities"):
+		if _root != null and _root.visible:
+			close()
+		else:
+			open()
+		get_viewport().set_input_as_handled()
+		return
+	# Escape — close if open.
+	if event.is_action_pressed("cancel") and _root != null and _root.visible:
+		close()
+		get_viewport().set_input_as_handled()
+		return
+
+
 func _on_backdrop_input(event: InputEvent) -> void:
 	# Tap on the backdrop (outside the panel) closes the matrix.
 	if event is InputEventMouseButton and event.pressed and event.button_index == MOUSE_BUTTON_LEFT: