feat: add language column, AI Generated category, and mine/shared filters

- Add language column (powershell/bash/python) to script_templates model and schemas
- Seed 'AI Generated' script category via migration 063
- Add mine and shared query params to list_templates endpoint

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/schemas/script_template.py

@@ -62,6 +62,7 @@ class ScriptTemplateCreate(BaseModel):
     estimated_runtime: Optional[str] = None
     requires_elevation: bool = False
     requires_modules: list[str] = Field(default_factory=list)
+    language: str | None = None
 
 class ScriptTemplateUpdate(BaseModel):
     name: Optional[str] = Field(None, min_length=1, max_length=200)
@@ -93,6 +94,7 @@ class ScriptTemplateListItem(BaseModel):
     requires_modules: list[str]
     is_verified: bool
     usage_count: int
+    language: str | None = None
 
     class Config:
         from_attributes = True