Add tags prominence and SIM source grouping features

Database changes:
- Add sim_source_id column to artifacts table for grouping multiple artifacts
- Create Alembic migration (001_add_sim_source_id) for schema update
- Add Alembic env.py for migration support with environment-based DB URLs

API enhancements:
- Add sim_source_id parameter to upload endpoint
- Add sim_source_id filter to query endpoint
- Add new /grouped-by-sim-source endpoint for getting artifacts by group
- Update all API documentation to include sim_source_id

UI improvements:
- Make tags required field and more prominent in upload form
- Add tags display directly in artifacts table (below filename)
- Add SIM Source ID field in upload form with helper text for grouping
- Update table to show sim_source_id (falls back to test_suite if null)
- Tags now displayed as inline badges in main table view

Seed data updates:
- Generate sim_source_id for 70% of artifacts to demonstrate grouping
- Multiple artifacts can share same sim_source_id
- Improved seed data variety with tag combinations

Features:
- Tags are now prominently displayed in both table and detail views
- Multiple artifacts can be grouped by SIM source ID
- Users can filter/query by sim_source_id
- Backward compatible - existing artifacts without sim_source_id still work

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/models/artifact.py

@@ -21,6 +21,9 @@ class Artifact(Base):
     test_config = Column(JSON)
     test_result = Column(String(50), index=True)  # pass, fail, skip, error
 
+    # SIM source grouping - allows multiple artifacts per source
+    sim_source_id = Column(String(100), index=True)  # Groups artifacts from same SIM source
+
     # Additional metadata
     custom_metadata = Column(JSON)
     description = Column(Text)