Add EXIF search infrastructure (Phase 1 & 2)

Implements foundation for EXIF-based photo search capabilities:

- Add geo.rs module with GPS distance calculations (Haversine + bounding box)
- Extend FilesRequest with EXIF search parameters (camera, GPS, date, media type)
- Add MediaType enum and DateTakenAsc/DateTakenDesc sort options
- Create date_taken index migration for efficient date queries
- Implement ExifDao methods: get_exif_batch, query_by_exif, get_camera_makes
- Add FileWithMetadata struct for date-aware sorting
- Implement date sorting with filename extraction fallback
- Make extract_date_from_filename public for reuse

Next: Integrate EXIF filtering into list_photos() and enhance get_all_tags()

src/memories.rs

@@ -232,7 +232,7 @@ fn extract_metadata_timestamps(
     (created, modified)
 }
 
-fn extract_date_from_filename(filename: &str) -> Option<DateTime<FixedOffset>> {
+pub fn extract_date_from_filename(filename: &str) -> Option<DateTime<FixedOffset>> {
     let build_date_from_ymd_capture =
         |captures: &regex::Captures| -> Option<DateTime<FixedOffset>> {
             let year = captures.get(1)?.as_str().parse::<i32>().ok()?;