Remove the unexported applyMigrations() and the runMigrations() method.
ApplyMigrations() is now the single implementation, accepting context
and an optional logger. connect() calls it directly.
All callers updated to pass context.Background() and nil logger.
Migration filenames now follow the pattern <version>_<description>.sql
(e.g. 001_initial_schema.sql). The version stored in schema_migrations
is the numeric prefix only, not the full filename stem.
Changes:
- Add ParseMigrationVersion() to extract numeric prefix from filenames
- Validate version is purely numeric, reject malformed filenames
- Rename 001.sql to 001_initial_schema.sql for clarity
- Deduplicate runMigrations/ApplyMigrations via shared applyMigrations()
- Add comprehensive unit tests for version parsing and migration apply
Closes#28
