Dates: serve the display wall clock (wall_clock) to clients

Every payload a client renders a capture time from now carries
`wall_clock`, a naive ISO-8601 string computed by the existing
`date_view::row_display_wall`: the camera's wall clock (true instant +
camera offset; the owner's display zone without an offset), with the
per-source fallback for unconverted rows. Clients render it verbatim and
do no zone math, which is the FileViewer-React #33 / Apollo #37 flip with
the rule kept server-side: the drain's permanent `date_utc IS NULL` floor
(#120: edited/exported files) would otherwise force every client to
carry the per-source legacy conventions forever, and insight prompts
already use the same function, so prompt and UI agree by construction.

- `/image/metadata` (+ the GPS / date / date-clear mutation responses):
  `file_wall_clock` — the row's wall, else the filename-class date, else
  the earliest fs time in the display zone (unindexed files).
- `/memories` items and `/photos/gps-summary` photos: `row_wall_clock`.
- `get_all_with_gps` returns full rows instead of a 7-tuple that dropped
  `date_taken_source`, which unconverted rows need.
- `date_view::owner_display_zone` resolves prefs -> app default per request.

Legacy fields are untouched, so current clients see byte-identical
responses (additive; safe to deploy ahead of the client flip, per #120).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/files.rs

@@ -1100,27 +1100,24 @@ pub async fn get_gps_summary(
     let mut exif_dao_guard = exif_dao.lock().expect("Unable to get ExifDao");
     match exif_dao_guard.get_all_with_gps(&requested_path, recursive) {
         Ok(gps_data) => {
+            let display_zone = crate::date_view::owner_display_zone(&app_state.user_ai_prefs_dao);
+            let server_zone = crate::camera_tz::server_zone();
             let mut photos: Vec<GpsPhotoSummary> = gps_data
                 .into_iter()
-                .map(
-                    |(
-                        path,
-                        lat,
-                        lon,
-                        date_taken,
-                        date_utc,
-                        camera_offset_minutes,
-                        date_taken_tz_source,
-                    )| GpsPhotoSummary {
-                        path,
-                        lat,
-                        lon,
-                        date_taken,
-                        date_utc,
-                        camera_offset_minutes,
-                        date_taken_tz_source,
-                    },
-                )
+                .filter_map(|row| {
+                    let wall_clock =
+                        crate::date_view::row_wall_clock(&row, display_zone, server_zone);
+                    Some(GpsPhotoSummary {
+                        lat: row.gps_latitude? as f64,
+                        lon: row.gps_longitude? as f64,
+                        path: row.file_path,
+                        date_taken: row.date_taken,
+                        date_utc: row.date_utc,
+                        camera_offset_minutes: row.camera_offset_minutes,
+                        date_taken_tz_source: row.date_taken_tz_source,
+                        wall_clock,
+                    })
+                })
                 .collect();
 
             // Sort by date_taken based on request, defaulting to ascending (oldest to newest)
@@ -1632,18 +1629,7 @@ mod tests {
             &mut self,
             _base_path: &str,
             _recursive: bool,
-        ) -> Result<
-            Vec<(
-                String,
-                f64,
-                f64,
-                Option<i64>,
-                Option<i64>,
-                Option<i32>,
-                Option<String>,
-            )>,
-            DbError,
-        > {
+        ) -> Result<Vec<crate::database::models::ImageExif>, DbError> {
             todo!()
         }