feat: migrate tags and contributors from TEXT to TEXT[] arrays

Convert tags and contributors columns from comma-separated strings to PostgreSQL
TEXT[] arrays for better data normalization and query performance.

Database Changes:
- schema.sql: Change tags/contributors from TEXT to TEXT[]
- schema.sql: Add GIN indexes for fast array searches
- queries.sql: Update search queries to use ANY() operator
- queries.sql: Update fuzzy search with unnest() for arrays

Generated Code (sqlc):
- models.go: Auto-generated with []string types for tags/contributors
- queries.sql.go: Auto-generated with proper array handling

Handler Changes:
- media.go: Update request structs to use []string for tags/contributors
- media.go: Remove pgtype.Text wrapping, use direct array assignment
- media.go: Add tag normalization in CreateMediaItemHandler
- collections.go: Update tags evaluation to join arrays for comparison
- collections.go: Add strings import for Join() function

Service Changes:
- ebook_scanner.go: Update EbookMetadata struct to use []string
- ebook_scanner.go: Remove string Join(), assign arrays directly
- collection_service.go: Update tags rule evaluation to join arrays
- collection_service.go: Add strings import

New Utilities:
- internal/utils/tags.go: Create NormalizeTags(), JoinTags(), SplitTags()
- Normalizes tags by trimming, lowercasing, removing duplicates/empties

API Documentation:
- bruno/media-items/Create Media Item.bru: Update examples to use arrays
- bruno/media-items/Update Media Item.bru: Update examples to use arrays
- Update docs: tags/contributors now array of string

Breaking Change:
- JSON format changes from "tags": "tag1,tag2" to "tags": ["tag1", "tag2"]
- Tests already use array format (no changes needed)

Benefits:
- GIN indexes enable faster array searches
- Normalization prevents data quality issues (case, duplicates)
- Array operations use PostgreSQL native operators (ANY, &&, unnest)
- Better separation of concerns (no string parsing in application)

database/schema/schema.sql

@@ -88,11 +88,11 @@ CREATE TABLE media_items (
     cover_image_path VARCHAR(500),
     series VARCHAR(255),
     series_number INTEGER,
-    tags TEXT,
+    tags TEXT[],
     asin VARCHAR(20), -- Still relevant for ebooks
     date_published DATE,
     publisher VARCHAR(255),
-    contributors TEXT,
+    contributors TEXT[],
     -- Enhanced fields for better metadata and functionality
     language VARCHAR(10) DEFAULT 'en', -- Language code (ISO 639-1)
     edition VARCHAR(100), -- Edition information
@@ -119,6 +119,10 @@ CREATE TABLE media_items (
     kobo_metadata JSONB
 );
 
+-- Add GIN indexes for fast array searches
+CREATE INDEX idx_media_items_tags_gin ON media_items USING GIN (tags);
+CREATE INDEX idx_media_items_contributors_gin ON media_items USING GIN (contributors);
+
 -- Create reading_progress table
 CREATE TABLE reading_progress (
     id UUID PRIMARY KEY DEFAULT gen_random_uuid(),