Refine manage overlay: US/CAN state abbreviations, share-QR caption, and an escalating second menu with named-face labels

Two rounds of follow-up work on the manage-button overlay:

1. Location formatting: US/Canada now show abbreviated state/province
   ("CA", "ON") instead of the full name, other countries show the full
   country name, and each is its own line (was one line, now wraps to
   two) so longer international place names have more room without
   threatening to overlap the top-right QR box. The bottom-left share QR
   also gets a "SCAN TO DOWNLOAD" caption.

2. Escalating menu: pressing the manage button again while its overlay
   is already up adds a second level -- each Immich-identified person's
   name labeled next to their face in the photo (using Immich's own
   face recognition/People data, no detection/recognition added to this
   project). A third press exits immediately instead of waiting out the
   30s auto-revert timer. No new Immich API needed -- GET /api/faces
   already embeds a nullable person.name per face; new
   server/app/face_labels.py maps a named face's box into the final
   800x480 frame's pixel space (reusing crop-box math extracted from
   image_pipeline.py's face-aware cropping). Capped at 4 named faces,
   sized to a real firmware RAM budget: each label is its own malloc'd
   overlay region on the device, alongside the 4 fixed corner regions
   already in use. New GET /frame/face-labels returns a flattened
   fixed-slot JSON shape (not a real array) so firmware's existing
   flat-scalar parser can read it without needing an actual array
   parser. No persistent state needed for the escalation itself -- it's
   all local control flow within one continuous awake session
   (frame_client.c's run_management_menu()).

server/README.md

@@ -48,13 +48,16 @@ algorithm itself -- it just streams the response straight to the panel.
   button (see `firmware/README.md`).
 - `GET /frame/config` -- `{"refresh_interval_s": ...}`, polled by the frame
   each wake alongside its reachability check
-- `GET /frame/photo-info` -- `{"asset_id": ..., "location": ... | null,
-  "taken_at": ... | null}` for the current photo (same idempotent
-  current-photo semantics as `/frame/image`). `location` is `city, state`
-  (or `city, country`, or just `city`) if Immich reverse-geocoded the
-  photo's GPS EXIF, else `null`; `taken_at` is `MM/DD/YY` from the
-  photo's EXIF capture date, else `null`. Used by the device's manage
-  button to build its overlay text
+- `GET /frame/photo-info` -- `{"asset_id": ..., "location_line1": ... |
+  null, "location_line2": ... | null, "taken_at": ... | null}` for the
+  current photo (same idempotent current-photo semantics as
+  `/frame/image`). `location_line1`/`location_line2` are `city` /
+  `state-or-country` if Immich reverse-geocoded the photo's GPS EXIF
+  (both `null` if not) -- for US/Canada, the region line is the
+  abbreviated state/province (`"CA"`, `"ON"`); elsewhere it's the full
+  country name. `taken_at` is `MM/DD/YY` from the photo's EXIF capture
+  date, else `null`. Used by the device's manage button to build its
+  overlay text
 - `GET /frame/share/{asset_id}` -- creates a 30-minute public, view-only
   Immich share link for `asset_id` and redirects (302) to it. Only works
   for the photo currently showing or in the upcoming queue on this frame
@@ -62,6 +65,13 @@ algorithm itself -- it just streams the response straight to the panel.
   (i.e. when someone actually scans the manage overlay's share QR), not
   when the button's pressed, so the 30-minute window starts when it's
   actually used
+- `GET /frame/face-labels` -- `{"count": N, "name_0": ..., "x_0": ...,
+  "y_0": ..., ...}` (up to 4 slots) -- named people from Immich's face
+  recognition, positioned in final 800x480 frame pixel space. Only faces
+  Immich already has an identified name for are included (no face
+  detection/recognition happens in this project, see
+  `app/face_labels.py`); `count: 0` if none are named. Used by the
+  device manage button's escalated second menu level
 - `GET /api/queue` -- `{"current": {...} | null, "upcoming": [...]}`, each
   entry an asset id + thumbnail URL; used by the config UI
 - `POST /api/queue/reorder` -- reorders the upcoming queue; body is