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/memories.rs

@@ -164,6 +164,10 @@ pub struct MemoryItem {
     pub date_utc: Option<i64>,
     pub camera_offset_minutes: Option<i32>,
     pub date_taken_tz_source: Option<String>,
+    /// Capture wall clock to display, naive ISO-8601 (`row_display_wall`):
+    /// the camera's clock, which can differ from the owner's day that
+    /// `created` groups under. Render verbatim (ADR-0001).
+    pub wall_clock: Option<String>,
 }
 
 #[derive(Debug, Serialize)]
@@ -648,6 +652,7 @@ pub fn gather_memory_items(
             }
 
             let created = crate::date_view::row_true_instant(&row, display_zone, server_zone);
+            let wall_clock = crate::date_view::row_wall_clock(&row, display_zone, server_zone);
             memories_with_dates.push((
                 MemoryItem {
                     path: row.file_path,
@@ -657,6 +662,7 @@ pub fn gather_memory_items(
                     date_utc: row.date_utc,
                     camera_offset_minutes: row.camera_offset_minutes,
                     date_taken_tz_source: row.date_taken_tz_source,
+                    wall_clock,
                 },
                 display_day,
             ));
@@ -1141,6 +1147,7 @@ mod tests {
                     date_utc: None,
                     camera_offset_minutes: None,
                     date_taken_tz_source: None,
+                    wall_clock: None,
                 },
                 NaiveDate::from_ymd_opt(2024, 1, 15).unwrap(),
             ),
@@ -1153,6 +1160,7 @@ mod tests {
                     date_utc: None,
                     camera_offset_minutes: None,
                     date_taken_tz_source: None,
+                    wall_clock: None,
                 },
                 NaiveDate::from_ymd_opt(2020, 1, 15).unwrap(),
             ),
@@ -1165,6 +1173,7 @@ mod tests {
                     date_utc: None,
                     camera_offset_minutes: None,
                     date_taken_tz_source: None,
+                    wall_clock: None,
                 },
                 NaiveDate::from_ymd_opt(2021, 1, 16).unwrap(),
             ),
@@ -1506,6 +1515,7 @@ mod tests {
                 date_utc: None,
                 camera_offset_minutes: None,
                 date_taken_tz_source: None,
+                wall_clock: None,
             };
             let v: serde_json::Value =
                 serde_json::to_value(&MemoriesResponse { items: vec![item] }).unwrap();