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.

autoload/strings.gd

@@ -196,6 +196,18 @@ const TABLE: Dictionary = {
 	&"tool.workbench_cremation_pyre":     "Cremation Pyre",
 	&"tool.stockpile_general":            "Stockpile",
 	&"tool.graveyard":                    "Graveyard",
+	&"ui.bill.mode_forever":              "Forever",
+	&"ui.bill.mode_count":                "Do X times",
+	&"ui.bill.mode_until_n":              "Do until X",
+	&"ui.bill.target":                    "Target",
+	&"ui.bill.until_count":               "Until count",
+	&"ui.bill.completed":                 "Done",
+	&"ui.bill.pause":                     "Pause",
+	&"ui.bill.remove":                    "Remove",
+	&"ui.bill.add_button":                "Add bill",
+	&"ui.bill.no_bills_hint":             "No bills. Add one to start crafting.",
+	&"ui.workbench.current_bill":         "Current",
+	&"ui.workbench.idle":                 "Idle",
 }