fix: nil-guard in _invoke_context_menu + README English

- _invoke_context_menu now early-returns if locale_factory()
  returns nil mid-frame, symmetric with build_rows. Prevents the
  race where a workbench destroyed between render and right-click
  would propagate nil locale into ctx_inner and crash craft.
- README v0.2.0 sections (M.create + action-callback) translated
  from Denglisch to English for consistency with the rest of the
  file.

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

README.md

@@ -105,15 +105,15 @@ there propagate (consistent with rest of the lib stack).
 
 ### `display.create(arg, opts) -> widget_def`
 
-Creates a crafting widget. **`arg`** ist eines von:
+Creates a crafting widget. **`arg`** is one of:
 
-- **Form 1 (Bw-Compat v0.1):** bare container-entity-handle. Intern
-  als constant locale_factory gewrappt (`function() return arg end`).
-- **Form 2 (v0.2 NEU):** `function() -> locale` — wird pro Frame
-  aufgerufen. Locale ist entweder ein entity-handle (Form-1 sub-
-  semantik) oder eine Table `{sources={...}, sink=...}`. Forward-
-  compat zu dynamischen Topologien (player-bewegt-sich →
-  adjacent-Container-Set ändert sich, ohne widget-Recreate).
+- **Form 1 (bw-compat from v0.1):** bare container-entity-handle. Wrapped
+  internally as a constant locale_factory (`function() return arg end`).
+- **Form 2 (NEW in v0.2):** `function() -> locale` — invoked per frame.
+  Locale is either an entity-handle (Form-1 sub-semantics) or a table
+  `{sources={...}, sink=...}`. Forward-compatible with dynamic
+  topologies (player moves → adjacent-container set changes, no widget
+  recreate required).
 
 **Syntax:** `display.create(arg: entity | function() -> locale, opts: table|nil) -> widget_def`
 
@@ -157,24 +157,23 @@ Loud-error if `arg` is `nil`.
 
 ---
 
-### Action-Callback Signatur (v0.2.0 Update)
+### Action-Callback Signature (v0.2.0 Update)
 
-Callbacks erhalten `(recipe_id, ctx_inner)` wo `ctx_inner`:
+Callbacks receive `(recipe_id, ctx_inner)` where `ctx_inner` is:
 
 ```lua
 {
-    locale     = <currently-resolved locale>,    -- v0.2 NEU
+    locale     = <currently-resolved locale>,    -- NEW in v0.2
     container  = <sink (Form-2) or handle (Form-1)>,  -- bw-compat alias
     close_menu = function() ... end,
     refresh    = function() ... end,
 }
 ```
 
-Modul-Aktion ruft typisch `crafting.craft(recipe_id,
-ctx_inner.locale, ctx)`. Existing v0.1 callers die
-`ctx_inner.container` benutzen funktionieren weiter via Form-1
-bw-compat-shim (sink-handle wird intern als single-container
-behandelt).
+Module action typically calls `crafting.craft(recipe_id,
+ctx_inner.locale, ctx)`. Existing v0.1 callers that use
+`ctx_inner.container` continue to work via the Form-1 bw-compat shim
+(sink-handle is treated internally as a single-container).
 
 ---