feat: sync all 140 Microsoft skills with collision protection

- Add find_github_skills() to discover skills in .github/skills/ not
  reachable via the skills/ symlink tree (picks up 11 missing skills)
- Add collision protection: if a target directory exists and was not
  from a previous Microsoft sync, append -ms suffix instead of overwriting
- Microsoft mcp-builder → mcp-builder-ms (community version preserved)
- Microsoft skill-creator → skill-creator-ms (community version preserved)
- Total skills: 856 (was 845, +11 newly discovered)

skills/pydantic-models-py/SKILL.md

@@ -0,0 +1,58 @@
+---
+name: pydantic-models-py
+description: Create Pydantic models following the multi-model pattern with Base, Create, Update, Response, and InDB variants. Use when defining API request/response schemas, database models, or data validation in Python applications using Pydantic v2.
+---
+
+# Pydantic Models
+
+Create Pydantic models following the multi-model pattern for clean API contracts.
+
+## Quick Start
+
+Copy the template from [assets/template.py](assets/template.py) and replace placeholders:
+- `{{ResourceName}}` → PascalCase name (e.g., `Project`)
+- `{{resource_name}}` → snake_case name (e.g., `project`)
+
+## Multi-Model Pattern
+
+| Model | Purpose |
+|-------|---------|
+| `Base` | Common fields shared across models |
+| `Create` | Request body for creation (required fields) |
+| `Update` | Request body for updates (all optional) |
+| `Response` | API response with all fields |
+| `InDB` | Database document with `doc_type` |
+
+## camelCase Aliases
+
+```python
+class MyModel(BaseModel):
+    workspace_id: str = Field(..., alias="workspaceId")
+    created_at: datetime = Field(..., alias="createdAt")
+    
+    class Config:
+        populate_by_name = True  # Accept both snake_case and camelCase
+```
+
+## Optional Update Fields
+
+```python
+class MyUpdate(BaseModel):
+    """All fields optional for PATCH requests."""
+    name: Optional[str] = Field(None, min_length=1)
+    description: Optional[str] = None
+```
+
+## Database Document
+
+```python
+class MyInDB(MyResponse):
+    """Adds doc_type for Cosmos DB queries."""
+    doc_type: str = "my_resource"
+```
+
+## Integration Steps
+
+1. Create models in `src/backend/app/models/`
+2. Export from `src/backend/app/models/__init__.py`
+3. Add corresponding TypeScript types