Workbench bill editor — tap a workbench, see/edit bills

Tap-to-select chain extended to workbenches (pawn always wins on shared
tile). Mutually exclusive with pawn selection via EventBus —
selecting one clears the other.

New WorkbenchPanel (scenes/ui/workbench_panel.gd, ~432 LOC, layer 18,
right-anchored 360 px) mirrors PawnDetailPanel shape. Bill rows expose
recipe name, mode (FOREVER / COUNT / UNTIL_N), target count, completed
progress, pause, and remove. Add-bill popup filters RecipeCatalog.all()
by accepted_skill so a Hearth only offers cooking recipes.

Supporting plumbing:
- EventBus.workbench_selected / workbench_deselected signals.
- Workbench.remove_bill() — interrupts mid-craft cleanly via
  on_craft_interrupted() before erasing.
- RecipeCatalog.all() static enumerator + Recipe.display_name() helper.
- World.workbench_at_tile() lookup.
- i18n keys ui.bill.* and ui.workbench.* in strings.gd.

Closes the deferred Phase 17 "Bill UI for workbenches" item. Player-
built workbenches are now functionally configurable; before this
landed, only world.gd-hardcoded bills worked.

scenes/ai/recipe_catalog.gd

@@ -109,3 +109,17 @@ static func cremate_corpse() -> Recipe:
 	r.required_skill = &"manual_labor"
 	r.skill_threshold = 0
 	return r
+
+
+## Returns one fresh instance of every recipe in the catalog. Used by UI
+## recipe-pickers to enumerate available bills; callers filter by
+## `recipe.required_skill` against the workbench's `accepted_skill`.
+static func all() -> Array[Recipe]:
+	return [
+		plank(),
+		stone_block(),
+		flour(),
+		bread(),
+		meal_from_vegetables(),
+		cremate_corpse(),
+	]