build(solo): offline queue 128 on the nRF52 builds

The phone app's offline queue took 256 x 177 B = 45 KB, which with the
on-device UI left the L1 ~5 KB of heap from boot (the sign buffer of #38
never fit). The UI keeps its own message history, and a full queue drops
the oldest channel messages first, so 128 is plenty: the L1 heap now has
~27 KB free. L1 OLED / e-ink, ProMicro, T-Echo Lite, both GAT562; the
upstream variants/ are unchanged (build_unflags in solo/).

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

solo/lilygo_techo_lite/platformio.ini

@@ -12,7 +12,10 @@ board_upload.maximum_size = 712704
 ; (≈ -O3 + -ffast-math), which bloats flash by ~200 KB on this feature-rich
 ; solo build. -Os keeps every feature, fits comfortably, and is actually safer
 ; for float (no fast-math reassociation). Speed is irrelevant for the UI/mesh.
-build_unflags = -Ofast
+; The offline queue (messages held for the phone app while it's away) at 128,
+; not the board's 256: on the nRF52 the 256 x 177 B left ~5 KB of heap next to
+; the on-device UI (which keeps its own history), too little for a sign buffer.
+build_unflags = -Ofast -D OFFLINE_QUEUE_SIZE=256
 build_flags =
   ${LilyGo_T-Echo-Lite.build_flags}
   -I src/helpers/ui
@@ -23,7 +26,7 @@ build_flags =
   ; -D QSPIFLASH=1
   -D BLE_PIN_CODE=123456
   ; -D BLE_DEBUG_LOGGING=1
-  -D OFFLINE_QUEUE_SIZE=256
+  -D OFFLINE_QUEUE_SIZE=128
   -D UI_RECENT_LIST_SIZE=9
   -D UI_SENSORS_PAGE=1
   ; -D MESH_PACKET_LOGGING=1