build(solo): the 4.26" panel as a fourth L1 e-ink env

WioTrackerL1Eink426_solo_dual extends eink_solo like the 4.2" build and
sets only what differs: the panel, rotation, the 9x15 at 2x with Text and
Icon size, bulk writes at 8 MHz, 250 contacts and a 32-message queue.
Replaces the full copy of the flags in solo/wio-tracker-l1-gdeq0426/.
Docs: advert precision, text and icon size, the 4.26" in the feature matrix.

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

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

@@ -10,7 +10,7 @@
 ; portrait keeps the 6x9, whose narrow width wants the smaller cell. The
 ; joystick reads upright with the panel at rotation 1 (landscape) and turns
 ; with it (JOYSTICK_UPRIGHT_ROTATION). A third for a 4.2" 400x300 panel on the
-; same wiring, in the 9x15.
+; same wiring, in the 9x15, and a fourth for a 4.26" 800x480 one.
 ;
 ; All: Dual BLE+USB with added Solo.
 [eink_solo]
@@ -58,3 +58,25 @@ build_flags = ${eink_solo.build_flags}
   -D DISPLAY_ROTATION=0
   -D JOYSTICK_UPRIGHT_ROTATION=0
   -D EINK_LARGE_FONT=2
+
+; A 4.26" 800x480 panel (Good Display GDEQ0426T82) on the same 24-pin FPC.
+; Native landscape; the 9x15 font at 2x (~44 characters x 16 lines), with
+; Settings > Display > Text size and Icon size (EINK_FONT_SCALE,
+; STATUS_ICON_SCALE). Rows sent to the panel in bulk at 8 MHz
+; (EINK_FAST_WRITES, GxEPD2_FastWrite.h). Its 48 KB framebuffer leaves the
+; heap short at boot, so fewer contacts and a smaller offline queue.
+[env:WioTrackerL1Eink426_solo_dual]
+extends = eink_solo
+build_unflags = ${eink_solo.build_unflags} -D EINK_DISPLAY_MODEL=GxEPD2_213_B74 -D DISPLAY_ROTATION=1
+  -D JOYSTICK_UPRIGHT_ROTATION=1 -D MAX_CONTACTS=350 -D OFFLINE_QUEUE_SIZE=128
+build_flags = ${eink_solo.build_flags}
+  -D EINK_DISPLAY_MODEL=GxEPD2_426_GDEQ0426T82
+  -D DISPLAY_ROTATION=0
+  -D JOYSTICK_UPRIGHT_ROTATION=0
+  -D EINK_LARGE_FONT=2
+  -D EINK_FONT_SCALE=2
+  -D STATUS_ICON_SCALE=0
+  -D EINK_FAST_WRITES=1
+  -D EINK_SPI_HZ=8000000
+  -D MAX_CONTACTS=250
+  -D OFFLINE_QUEUE_SIZE=32