refactor: remove Phase X terminology from source code comments
Remove planning document phase references from code comments:
app_test.go:
- Remove Phase 5 references from 8 test function comments
querier.go & queries.sql.go:
- Remove Phase 1, 2, 3, 4, 6 references from section headers
- Clean up week numbers (Weeks 5-6, Week 3-4, etc.)
queries.sql:
- Remove Phase 4 references from Kobo queries
kobo.go:
- Remove Phase 6 references from ContentId mapping comments
progress.go:
- Remove Phase 1 reference from route comment
media_scanner.go & media_scanner_library_type_test.go:
- Remove Phase 2 references from library type scanning comments
schema.sql:
- Remove Phase 1, 2, 3, 4, 5, 7 references from table/section comments
- Clean up: Format Detection, Progress Tracking, Device Registry,
Sync Queue, Conflict Resolution, Reading History, Indexes, etc.
test_helpers.go:
- Remove Phase 6 reference from handler setup comment
These phase numbers were from internal planning documents and have no
meaning in the codebase. Removing them makes the code self-documenting.