feat(ui): make favourites mean one thing across every list

Three names had grown around one idea. "Favourite" was a filter in
Settings, an invisible app-only flag on a contact, a device-settable bit on
a channel, and — on the Nodes screen — a menu row that actually pinned to
the Favourites dial. Nothing marked a favourite on screen, and the dial
only took chat contacts.

A favourite is now the starred flag (ContactInfo::flags bit 0 for contacts
and rooms, ch_fav_bitmask for channels), settable on the device everywhere
via a Fav: ON/OFF row, marked with a star on its row, and sorted to the top
of the list — in Messages, Tools > Nodes and the Locator target picker.
Settings > Contacts > "Favs top" turns the sorting off; it defaults on, and
is stored inverted so an upgraded prefs file reads back as on rather than
off.

MyMesh::setContactFavourite() writes the same bit the app sets and bumps
lastmod, so the two stay in sync. The DMs/Rooms = Fav list filters no
longer depend on having starred someone in the app first.

Pinning is now separate and explicit, and the dial takes contacts, room
servers and channels. Slots carry a kind (NodePrefs::favourite_kinds,
schema 0xC0DE0029) — a channel slot holds an index, so emptiness is decided
by the kind first, since channel 0's payload is all zeroes. Choosing what
to pin reuses the Messages screen's own Direct/Channels/Rooms browse
instead of a second picker built on the dial, which drops that picker, its
key/label tables and the now-unused getRecentDMContacts(). A filled tile
gained Unpin/Replace under Hold Enter.

Fixes a room server being pinnable and then unremovable: the picker's
recent-conversations tier didn't filter by contact type and room posts
share the DM history, opening one from the dial skipped the login
handshake, and Unpin only existed in the chat contact list that rooms never
appear in.

Also: PopupMenu::_visible was written and never read (render recomputes the
cap from display height), which is why menus with more items than the
"visible" argument always worked; Settings' all/fav values and the
dm_show_all comment said things that were not true.

Built for Heltec V3, Wio Tracker L1, Wio Tracker L1 e-ink and T-Echo Card.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

examples/companion_radio/NodePrefs.h

@@ -87,7 +87,7 @@ struct NodePrefs {  // persisted to file
   char custom_msgs[10][140];   // user-defined quick messages (supports {loc}, {time})
   uint64_t ch_notif_override;  // bitmask: bit i = channel i has explicit notification setting [del→onChannelRemoved]
   uint64_t ch_notif_muted;     // bitmask: bit i = channel i muted (only if override bit set) [del→onChannelRemoved]
-  uint8_t  dm_show_all;        // 0=favourites only (default), 1=all chat contacts
+  uint8_t  dm_show_all;        // 0=favourites only, 1=all chat contacts (default)
   uint8_t  room_fav_only;      // 0=all room servers (default), 1=favourites only
   uint8_t  ringtone_bpm_idx;   // index into {60,90,120,150,180}
   uint8_t  ringtone_len;        // number of notes in custom ringtone (0 = use default)
@@ -143,11 +143,19 @@ struct NodePrefs {  // persisted to file
   uint8_t  page_order_set;      // 0xA5 = page_order is user-configured; anything else = use default
   static const uint8_t PAGE_ORDER_MAGIC = 0xA5;
 
-  // Favourites dial: 6 pinned contacts, stored as first 6 bytes of pub_key per slot.
-  // All-zero = empty slot (probability a real pub_key starts with 6 zero bytes is 2^-48).
-  // Layout transposes between landscape (3×2) and portrait (2×3).
+  // Favourites dial: 6 pinned targets. Layout transposes between landscape
+  // (3×2) and portrait (2×3). What a slot holds depends on favourite_kinds[]
+  // (stored at the struct tail, see there):
+  //   FAV_KIND_CONTACT — first 6 bytes of pub_key; covers chat contacts and
+  //     room servers alike. All-zero = empty slot (a real pub_key starts with
+  //     6 zero bytes with probability 2^-48).
+  //   FAV_KIND_CHANNEL — channel index in byte 0, rest zero. Never empty:
+  //     channel 0 is all-zero, so emptiness is decided by the kind first.
   static const uint8_t FAVOURITES_COUNT = 6;
   static const uint8_t FAVOURITE_PREFIX_LEN = 6;
+  static const uint8_t FAV_KIND_CONTACT = 0;
+  static const uint8_t FAV_KIND_CHANNEL = 1;
+  static const uint8_t FAV_KIND_MAX     = 1;
   uint8_t favourite_contacts[FAVOURITES_COUNT][FAVOURITE_PREFIX_LEN]; // [del→onContactRemoved]
 
   // GPS trail cadence. Logging on/off is a runtime state (Tools › Trail),
@@ -470,6 +478,16 @@ struct NodePrefs {  // persisted to file
   // companion's own messages send under, only what repeat_scope_only accepts.
   char     repeat_extra_scopes[24];
 
+  // What each favourite_contacts[] slot holds (see FAV_KIND_* by that field).
+  // Appended here, not next to it, because the on-disk format is append-only.
+  // Zero-init = every slot is a contact, which is what pre-0x28 saves are.
+  uint8_t  favourite_kinds[FAVOURITES_COUNT];  // [del→onChannelRemoved]
+
+  // Settings > Contacts > "Favs top". Stored inverted so that both a fresh
+  // memset and an older prefs file (no bytes here at all) mean "on", which is
+  // the default -- a positive flag would read back as off for every upgrader.
+  uint8_t  fav_sort_off;       // 0 = favourites first in every list (default), 1 = natural order
+
   // Single source of truth for the live-share option tables (shared by the Map
   // UI labels and the auto-send engine in UITask).
   static const uint8_t LOC_SHARE_MOVE_COUNT = 4;
@@ -537,7 +555,7 @@ struct NodePrefs {  // persisted to file
   // repeat_* fields) instead of at the tail, which shifted every field after
   // them by 25 bytes when loading an older file. Never released, but a dev
   // build wrote it, so the number must not be reused for anything else.
-  static const uint32_t SCHEMA_SENTINEL = 0xC0DE0027;
+  static const uint32_t SCHEMA_SENTINEL = 0xC0DE0029;
 
   // Bit-index for each home page. Used by page_order (entries store bit+1) and
   // by home_pages_mask. Single source of truth — both HomeScreen::pageBit/bitToPage
@@ -662,7 +680,12 @@ struct NodePrefs {  // persisted to file
 // the struct tail (the 0xC0DE0026 mid-stream layout was unreadable for older
 // files, see the sentinel comment) -- padding worked out identically either
 // way, so sizeof stays 2752. Confirmed via a real Heltec_v3 build.
-static_assert(sizeof(NodePrefs) == 2752,
+// favourite_kinds[6] (0xC0DE0028) added 8 bytes, not 6 -- the struct had no
+// spare tail padding left after 0xC0DE0026, so the 6 real bytes rounded up to
+// the next alignment boundary. Confirmed via a real Heltec_v3 build.
+// fav_sort_off (0xC0DE0029) landed in the 2 bytes of padding the 0xC0DE0028
+// bump left over -- confirmed via a real Heltec_v3 build, sizeof unchanged.
+static_assert(sizeof(NodePrefs) == 2760,
               "NodePrefs layout changed — sync DataStore save/load + clamp, bump "
               "SCHEMA_SENTINEL, then update this size (see steps above).");