feat(tags): Add database schema and tags module (v1.3.0 Phase 1)

Implements tag/category system backend following microformats2 p-category specification.

Database changes:
- Migration 008: Add tags and note_tags tables
- Normalized tag storage (case-insensitive lookup, display name preserved)
- Indexes for performance

New module:
- starpunk/tags.py: Tag management functions
  - normalize_tag: Normalize tag strings
  - get_or_create_tag: Get or create tag records
  - add_tags_to_note: Associate tags with notes (replaces existing)
  - get_note_tags: Retrieve note tags (alphabetically ordered)
  - get_tag_by_name: Lookup tag by normalized name
  - get_notes_by_tag: Get all notes with specific tag
  - parse_tag_input: Parse comma-separated tag input

Model updates:
- Note.tags property (lazy-loaded, prefer pre-loading in routes)
- Note.to_dict() add include_tags parameter

CRUD updates:
- create_note() accepts tags parameter
- update_note() accepts tags parameter (None = no change, [] = remove all)

Micropub integration:
- Pass tags to create_note() (tags already extracted by extract_tags())
- Return tags in q=source response

Per design doc: docs/design/v1.3.0/microformats-tags-design.md

Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

starpunk/micropub.py

@@ -318,7 +318,8 @@ def handle_create(data: dict, token_info: dict):
             content=content,
             published=True,  # Micropub posts are published by default
             created_at=published_date,
-            custom_slug=custom_slug
+            custom_slug=custom_slug,
+            tags=tags if tags else None  # Pass tags to create_note (v1.3.0)
         )
 
         # Build permalink URL
@@ -403,9 +404,9 @@ def handle_query(args: dict, token_info: dict):
         if note.title:
             mf2["properties"]["name"] = [note.title]
 
-        # Tags not implemented in V1, skip category property
-        # if hasattr(note, 'tags') and note.tags:
-        #     mf2["properties"]["category"] = note.tags
+        # Add tags if present (v1.3.0)
+        if note.tags:
+            mf2["properties"]["category"] = [tag["display_name"] for tag in note.tags]
 
         return jsonify(mf2), 200