fix: decode percent-encoded path in sqlite database URL

[AlisinaDevelo]

Closes #1256.

The sqlite driver built its DSN from purl.String(), which re-encodes the URL path. A database URL like sqlite:///Magic%20Data/db.sqlite was passed to sql.Open with the %20 intact, so it looked for a literal Magic%20Data file and failed to connect.

Now the DSN is built from the decoded path (still keeping any non-custom query params, e.g. sqlite pragmas). Added a test that opens a DB under a directory with a space in the name.

[coveralls]

coverage: 54.468% (+0.04%) from 54.432% — AlisinaDevelo:fix-sqlite-encoded-path into golang-migrate:master

[AlisinaDevelo]

Checking in on the SQLite URL fix. It decodes percent-encoded path components while preserving query parameters, and Go 1.24 and 1.25 tests, lint, and coverage checks are green. If this still fits the project’s direction, could someone take a look when there’s a chance? I’m happy to rebase or adjust the path handling.

[AlisinaDevelo]

Hey, checking in on the SQLite URL fix—does the path handling need anything else from me before review?