docs: update documentation for media scanner naming

- Update development.md with new file names (scanner.go, media_scanner.go)
- Update API reference: "Book/ebook operations" -> "Media item operations"
- Remove historical migration comments from schema:
  - Simplify media_items table comment
  - Remove backward compatibility comments for reading_progress and media_ratings
  - Remove note about backward compatibility views
- Remove historical comment from queries.sql about ebook folders

database/schema/schema.sql

@@ -74,7 +74,7 @@ CREATE TABLE library_visibility (
     UNIQUE(user_id, library_id)
 );
 
--- Create media_items table (replaces ebooks table for broader media support)
+-- Create media_items table
 CREATE TABLE media_items (
     id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
     library_id UUID NOT NULL REFERENCES libraries(id) ON DELETE CASCADE,
@@ -161,8 +161,7 @@ CREATE TABLE reading_progress (
     conflict_resolved BOOLEAN DEFAULT TRUE
 );
 
--- Create reading_progress view for backward compatibility
--- Create media_ratings table (replaces ebook_ratings)
+-- Create media_ratings table
 CREATE TABLE media_ratings (
     id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
     media_item_id UUID NOT NULL REFERENCES media_items(id) ON DELETE CASCADE,
@@ -460,7 +459,6 @@ COMMENT ON COLUMN media_items.google_books_id IS 'Google Books identifier for in
 -- - Library visibility is controlled through library_visibility table - admins can hide/show libraries per user
 -- - Notes and highlights support position data (page:offset or CFI format) for precise location tracking
 -- - Highlights can have associated notes for detailed annotations
--- NOTE: All backward compatibility views (ebooks, ebook_ratings, ebook_reading_progress, ebook_notes, ebook_highlights) have been removed
 
 -- ============================================
 -- PERFORMANCE OPTIMIZATION (Phase 7)