Add item tags to Thing model

Tags enable categorizing items for boundary checks and other systems.
Added tags field to Thing and ThingTemplate, updated load and spawn
functions to handle tags from TOML definitions.

src/mudlib/thing.py

@@ -20,3 +20,4 @@ class Thing(Object):
     portable: bool = True
     aliases: list[str] = field(default_factory=list)
     readable_text: str = ""
+    tags: list[str] = field(default_factory=list)

src/mudlib/things.py

@@ -30,6 +30,7 @@ class ThingTemplate:
     # Verb handlers (verb_name -> module:function reference)
     verbs: dict[str, str] = field(default_factory=dict)
     readable_text: str = ""
+    tags: list[str] = field(default_factory=list)
 
 
 # Module-level registry
@@ -61,6 +62,7 @@ def load_thing_template(path: Path) -> ThingTemplate:
         locked=data.get("locked", False),
         verbs=data.get("verbs", {}),
         readable_text=data.get("readable_text", ""),
+        tags=data.get("tags", []),
     )
 
 
@@ -89,6 +91,7 @@ def spawn_thing(
             portable=template.portable,
             aliases=list(template.aliases),
             readable_text=template.readable_text,
+            tags=list(template.tags),
             capacity=template.capacity,
             closed=template.closed,
             locked=template.locked,
@@ -103,6 +106,7 @@ def spawn_thing(
             portable=template.portable,
             aliases=list(template.aliases),
             readable_text=template.readable_text,
+            tags=list(template.tags),
             location=location,
             x=x,
             y=y,