EXIF GPS write: POST /image/exif/gps via exiftool

New endpoint accepts {path, library, latitude, longitude} and shells
out to exiftool to write GPSLatitude/GPSLongitude (with N/S, E/W refs)
into the file's EXIF in place. After the write, the handler
re-extracts EXIF and updates the image_exif row so the DB stays in
sync — the response carries the updated metadata block in one
round-trip. Falls through to store_exif if the row is missing.

`exif::write_gps` is the small helper. `-overwrite_original` so no
.orig sidecar is left behind. Validates lat/lon range + supports_exif
before spawning exiftool. Format support matches the existing read
path (JPEG / TIFF / RAW / HEIF / PNG / WebP) — videos still need a
different writer and aren't covered.

Apollo's "+ PIN" carousel button (separate commit on the Apollo side)
calls this through /api/photos/exif/gps. Drive-by: cargo fmt one-line
collapse on apollo_client.rs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/state.rs

@@ -1,6 +1,6 @@
+use crate::ai::apollo_client::ApolloClient;
 use crate::ai::insight_chat::{ChatLockMap, InsightChatService};
 use crate::ai::openrouter::OpenRouterClient;
-use crate::ai::apollo_client::ApolloClient;
 use crate::ai::{InsightGenerator, OllamaClient, SmsApiClient};
 use crate::database::{
     CalendarEventDao, DailySummaryDao, ExifDao, InsightDao, KnowledgeDao, LocationHistoryDao,