chore: remove obsolete community rating type change documentation

Remove COMMUNITY_RATING_TYPE_CHANGE.md as this was a planning document
for the community rating field type change (FLOAT4 → FLOAT8) which has
now been completed and integrated into the main implementation.

The community rating field is now:
- Type: DOUBLE PRECISION (FLOAT8) in database schema
- Range: 0.0-10.0 (not 0-5 like user ratings)
- Displayed on frontend with star rating and numeric score
- Properly distinguished from user ratings

This documentation is no longer needed since the feature is complete.

COMMUNITY_RATING_TYPE_CHANGE.md

@@ -1,118 +0,0 @@
-# community_rating Type Change: DECIMAL → DOUBLE PRECISION
-
-## Date
-March 30, 2026
-
-## Decision
-Changed `community_rating` from `DECIMAL(3,1)` to `DOUBLE PRECISION` in the implementation plan.
-
-## Rationale
-
-### Original Choice: DECIMAL(3,1)
-The schema was originally designed with:
-```sql
-community_rating DECIMAL(3,1)  -- 0.0-10.0 with 1 decimal place
-```
-
-**Reasoning:**
-- Exact decimal precision (avoids 8.4999999)
-- Distinguishes from user ratings (INTEGER 1-10 for half-star precision)
-- Matches metadata source format (decimal strings)
-
-### Problems with DECIMAL(3,1)
-
-1. **Awkward Go code** - Required conversion via `pgtype.Numeric`:
-   ```go
-   // Complex conversion needed
-   CommunityRating: func() pgtype.Numeric {
-       var n pgtype.Numeric
-       if metadata.CommunityRating > 0 {
-           n.Scan(fmt.Sprintf("%.1f", metadata.CommunityRating))
-       }
-       return n
-   }()
-   ```
-
-2. **Only DECIMAL column in database** - No existing pattern to follow
-
-3. **Unnecessary complexity** - ComicInfo.xml already uses float64, DECIMAL adds friction
-
-### New Choice: DOUBLE PRECISION
-
-Changed to:
-```sql
-community_rating DOUBLE PRECISION  -- 0.0-10.0
-```
-
-**Benefits:**
-
-1. **Simple Go code** - Direct assignment:
-   ```go
-   CommunityRating: pgtype.Float8{Float64: metadata.CommunityRating, Valid: true}
-   ```
-
-2. **Natural mapping** - ComicInfo.xml `float64` → PostgreSQL `DOUBLE PRECISION` → Go `pgtype.Float8`
-
-3. **No conversion overhead** - No string formatting, no Scan() method
-
-4. **Negligible precision loss** - Floating-point error < 0.00001% for 0-10 ratings
-
-5. **Consistent with codebase** - Uses standard pgtype pattern (like other float columns)
-
-## Impact
-
-### Files Changed in Implementation Plan
-
-1. **database/schema/schema.sql** (reference only)
-   - Already has DOUBLE PRECISION
-   - No action needed
-
-2. **internal/services/media_scanner.go**
-   - Simplified CreateMediaItem call
-   - Removed complex pgtype.Numeric conversion
-
-3. **internal/database/models.go** (sqlc generated)
-   - CommunityRating type: `pgtype.Numeric` → `pgtype.Float8`
-   - Will be auto-updated after schema change
-
-### Testing Implications
-
-None - the change is transparent to:
-- API consumers (JSON serialization unchanged)
-- Database queries (same range and comparison operations)
-- User interface (display format unchanged)
-
-## Migration Notes
-
-If you have an existing database with DECIMAL(3,1):
-
-```sql
--- Migration from DECIMAL to DOUBLE PRECISION
-ALTER TABLE media_items
-ALTER COLUMN community_rating TYPE DOUBLE PRECISION
-USING community_rating::DOUBLE PRECISION;
-```
-
-Since this is pre-production (no production deployments exist), use:
-```bash
-# Option 1: Recreate database (cleanest)
-podman compose down -v
-podman compose up -d
-
-# Option 2: Manual migration (preserves test data)
-podman exec bookhoard_db psql -U postgres -d bookhoard -c "
-ALTER TABLE media_items
-ALTER COLUMN community_rating TYPE DOUBLE PRECISION
-USING community_rating::DOUBLE PRECISION;
-"
-```
-
-## Conclusion
-
-The DOUBLE PRECISION choice provides:
-- ✅ Simpler, cleaner code
-- ✅ Better developer experience
-- ✅ Natural type mapping
-- ✅ No practical precision loss
-
-For a 0-10 rating scale, the theoretical precision advantage of DECIMAL is outweighed by the code simplicity benefit.