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/wio-tracker-l1-eink/platformio.ini

@@ -11,8 +11,12 @@ extends = WioTrackerL1Eink
 ; (≈ -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 = ${WioTrackerL1Eink.build_flags}
+  -D OFFLINE_QUEUE_SIZE=128
   -D DUAL_SERIAL=1
   -D ENABLE_SCREENSHOT
   -Os