modelgen: recurse through nested generics in list resolvers

_get_list_inner (Pydantic) and _resolve_ts_list (TypeScript) collapsed
nested generics to "str" / "string[]" — so List[List[int]] became
List[str] and List[Dict[str,Any]] became List[str]. Fix recurses on
list-of-list and falls back to Dict[str,Any] / Record<string,unknown>
for list-of-dict.

Regenerated outputs:
- core/gpu/models/models.py: SegmentFieldResponse.boundary now
  List[List[int]], unblocking /segment_field which was 500ing on every
  request with pydantic ValidationError
- core/db/models.py + ui/common/types/generated.ts: Brand.airings now
  matches its source schema (List[Dict[str,Any]] / Record<string,unknown>[])

core/db/models.py

@@ -164,7 +164,7 @@ class Brand(SQLModel, table=True):
     aliases: List[str] = Field(default_factory=list, sa_column=Column(JSON, nullable=False, server_default='[]'))
     source: BrandSource = "ocr"
     confirmed: bool = False
-    airings: List[str] = Field(default_factory=list, sa_column=Column(JSON, nullable=False, server_default='[]'))
+    airings: List[Dict[str, Any]] = Field(default_factory=list, sa_column=Column(JSON, nullable=False, server_default='[]'))
     total_airings: int = 0
     created_at: Optional[datetime] = Field(default_factory=datetime.utcnow)
     updated_at: Optional[datetime] = Field(default_factory=datetime.utcnow)