feat(home-pages): make Map and Shutdown reorderable; v1.22 notes

The Map page had no Settings entry and Shutdown was pinned to the end of the
carousel because page_order held only 11 slots — full in the common
GPS+SENSORS config, so both pages fell back to being appended at nav time and
couldn't be moved. Grow page_order to 13 (== HPB_COUNT) so every page has a
reorderable slot, and add Map + Shutdown to the default order and the
required-append list.

To keep the persisted format backward-compatible (page_order sits mid-record,
not at the tail), the on-disk head stays the original 11 bytes at its existing
offset and the 2 new slots are appended at the file tail, matching the
append-only schema design. Bump SCHEMA_SENTINEL to 0xC0DE0019; on a pre-0x19
save the tail bytes are the old sentinel/EOF, so they're clamped to 0 and
ensurePageOrderInit re-appends Map/Shutdown into the freed slots on first use.

Drop the now-dead Shutdown-eviction path (13 slots fit all pages).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

release-notes.md

@@ -1,3 +1,10 @@
+## MeshCore Solo Companion Firmware v1.22
+
+### Fixes
+
+- **Home page visibility no longer resets on update** — the prefs schema-migration that turned the **Favourites** page on ran on *every* firmware update (any schema-version bump), so a page you'd deliberately hidden kept coming back after each release. It's now gated to the single upgrade that introduced Favourites, so your hidden pages stay hidden.
+- **Map page in Home Pages settings** — the **Map** home page shipped with no entry under **Settings › Home Pages**, so it was always shown and couldn't be moved. It's now a first-class page there: **toggle its visibility** and **reorder it** like any other (visible by default; existing users keep it on). Reordering also now covers the **Shutdown** page, which was previously pinned to the end of the carousel.
+
 ## MeshCore Solo Companion Firmware v1.21
 
 ### What's new