The hub package promised consumers wouldn't need to import libfossil directly, but they still had to blank-import libfossil's SQL driver to satisfy the underlying db layer's registration requirement. Move the blank import into hub itself (hub/driver.go) so the package fulfills its own dependency.

Consumers like sesh can now reduce their main.go to a plain `import "github.com/danmestas/EdgeSync/hub"` (or whatever wrapper they use) without taking a direct dep on libfossil's internal SQL machinery.

modernc is registered as the production default. If a consumer ever needs ncruces (WASM/WASI), an escape hatch can be added then.

Tests in hub/ drop their now-redundant blank imports.

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> check-in: 754914fd82 user: [email protected] tags: trunk, v0.0.18