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.

Cargo.lock

@@ -1477,6 +1477,15 @@ dependencies = [
  "simple_asn1",
 ]
 
+[[package]]
+name = "kamadak-exif"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ef4fc70d0ab7e5b6bafa30216a6b48705ea964cdfc29c050f2412295eba58077"
+dependencies = [
+ "mutate_once",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.5.0"
@@ -1718,6 +1727,12 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "mutate_once"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13d2233c9842d08cfe13f9eac96e207ca6a2ea10b80259ebe8ad0268be27d2af"
+
 [[package]]
 name = "nu-ansi-term"
 version = "0.50.3"
@@ -1820,6 +1835,7 @@ dependencies = [
  "image",
  "infer",
  "jsonwebtoken",
+ "kamadak-exif",
  "md-5",
  "mimalloc",
  "mime_guess",