feat(photos): add EXIF metadata extraction and storage

Extract EXIF orientation, GPS coordinates, camera info, and timestamps
from uploaded images using kamadak-exif. Store metadata in a new
file_metadata PG table. Apply EXIF orientation to thumbnail generation
so images display correctly. Add /api/files/{id}/metadata endpoint.

src/infrastructure/services/thumbnail_service.rs

@@ -269,6 +269,15 @@ impl ThumbnailService {
             let img = image::load_from_memory(&data)
                 .map_err(|e| ThumbnailError::ImageError(e.to_string()))?;
 
+            // Apply EXIF orientation so thumbnails display correctly
+            let img = {
+                use crate::infrastructure::services::exif_service::{ExifService, apply_orientation};
+                let orientation = ExifService::extract(&data)
+                    .and_then(|m| m.orientation)
+                    .unwrap_or(1);
+                apply_orientation(img, orientation)
+            };
+
             // Calculate new dimensions preserving aspect ratio
             let (orig_width, orig_height) = (img.width(), img.height());
             let (new_width, new_height) = if orig_width > orig_height {
@@ -349,6 +358,15 @@ impl ThumbnailService {
                 let img = image::load_from_memory(&data)
                     .map_err(|e| ThumbnailError::ImageError(e.to_string()))?;
 
+                // Apply EXIF orientation so thumbnails display correctly
+                let img = {
+                    use crate::infrastructure::services::exif_service::{ExifService, apply_orientation};
+                    let orientation = ExifService::extract(&data)
+                        .and_then(|m| m.orientation)
+                        .unwrap_or(1);
+                    apply_orientation(img, orientation)
+                };
+
                 let (orig_w, orig_h) = (img.width(), img.height());
 
                 ThumbnailSize::all()