feat(sbase): migration 31->32 drops osm_way_cell for new 0.01° grid

Bumps AppDatabase to version 32 and adds MIGRATION_31_32 which DELETEs every osm_way_cell row. The cell-key encoding is a pure function of OsmGridIndex.CELL_E7 (now 100_000, was 800_000), so every row keyed under the old grid is silently wrong and the only safe option is to wipe and reindex from the preserved bbox columns.

Preserves osm_import + osm_way (including bbox_*_e7 columns) so the follow-up reindexer can rebuild the spatial index purely from already-decoded bbox data — no polyline decode, no re-download. osm_import is intentionally left alone so OsmImportDao.observeCount() stays >0 and DefaultSpeedLimitSource keeps reporting OSM mode; the temporary lookup gap is handled by the existing fallback to the fixed baseline (no throws).

Adds the paged OsmWayDao.pageBboxes(limit, offset) query + OsmWayBbox projection POJO the reindexer needs, and a Robolectric V31ToV32MigrationTest pinning row counts, schema/index preservation and idempotency.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: adsamcik