feat(ui-lvgl): 320x240 browser simulator, compose field fixes

Simulator: SIM_UI=lvgl variants/sim/build_wasm.sh builds ui-lvgl for the
browser. SimLcdDisplay blits LVGL's RGB565 flush to a 320x240 canvas and
LvglPort.h's sim branch feeds the mouse in as touch; LVGL comes from the
L2 env's libdeps, its objects cached in web/build/obj_lvgl/. web/lvgl.html
runs it beside a ui-new peer on a direct link, with a window.sim API for
headless checks. New hooks: sim_lcd_touch, sim_lcd_button,
sim_test_send_channel_msg.

Compose: the theme's padding left less than one line in the field, so it
scrolled vertically and text jumped; pad it to fit exactly one line. The
cursor is drawn only while FOCUSED, now set while the keyboard is up.
With the keyboard up the screen header hides so the conversation keeps a
message in view; the accent popup stays inside the keyboard, clear of the
field; channel bubbles put the age next to the sender (one line shorter);
the thread scrollbar shows only while scrolling.

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

docs/development/ui-core.md

@@ -146,7 +146,7 @@ consumes keys only.
 - LVGL 9 (pinned), memory in a PSRAM pool; partial-render buffers in internal RAM, flush over QSPI via LovyanGFX.
 - Theme tokens (colours, spacing, typography) in one place — the first chance to realise the "Amber Trace" direction in colour.
 - Fonts ✅ Noto Sans generated by `ui-lvgl/fonts/generate.sh` (lv_font_conv): European Latin (Latin-1, Extended-A/B), Greek, Cyrillic + supplement, typographic punctuation, currency, LVGL symbols; 12/14/16/20 px, clock 40 px digits only. On-screen keyboard (`ui-lvgl/Keyboard.h`), phone-style: one layout per script (Latin QWERTY / Cyrillic ЙЦУКЕН / Greek) chosen by the same `keyboard_main_alphabet` / `keyboard_alt_alphabet` prefs as `ui-new` (globe key switches), hold a key for its variants; compose limit counted in UTF-8 bytes. Long-press variants and UTF-8 case mapping are shared with `ui-new` in `ui-core/KeyboardData.h`.
-- Runs in the WASM sim at 320×240 with mouse as touch, so most UI work needs no flashing.
+- Simulator ✅: `SIM_UI=lvgl variants/sim/build_wasm.sh` builds the same `ui-lvgl` code for the browser (`SimLcdDisplay` in `variants/sim/SimDisplayDriver.h` blits LVGL's RGB565 flush to a 320×240 canvas; the `SIM_PLATFORM` branch of `ui-lvgl/LvglPort.h` feeds the mouse in as touch). LVGL comes from the L2 env's PlatformIO libdeps; its objects are cached in `web/build/obj_lvgl/`. `web/lvgl.html` runs it next to a `ui-new` peer on a direct link (buttons: advert, peer DM, peer → Public, the board button) and exposes `window.sim` (`tap`, `hold`, `touch`, `peerDM`, `peerChannel`) for headless checks.
 - PR #3381's LVGL UI is a reference for platform glue (flush, GT911, PSRAM pool) only; its screens are not adopted.
 
 ## Migration plan
@@ -159,7 +159,7 @@ checked in the sim plus on L1 hardware before the next one.
 2. **Engines, one per commit.** Clock tools ✅ (also introduced `ui-core/UiEvents.h`, the Core → frontend event queue; `UITask::tickCore()` runs `UiCore::loop()` and drains it) → ping ✅ → course-over-ground ✅ → live share ✅ → locator ✅ → trail ✅ → notifications ✅ (with step 3). `UITask` shrinks to screen management + drawing.
 3. **Flip the interface** ✅. `UiCore` is `MyMesh::Listener`; `ui-new`'s `UITask` derives `UITaskBase` + `UiCoreHost` and is fed by events, drained at the start (mesh-originated) and end (engines) of its `loop()`. Mesh callbacks no longer touch the display or buzzer directly.
 4. **Settings schema.** Convert `SettingsScreen` section by section.
-5. **`ui-lvgl` skeleton** ✅ on L2 hardware (env `Wio_Tracker_L2_companion_solo_lvgl`, LVGL 9.2.2): status bar, home, conversation list, contact picker, conversation with keyboard, toasts, display sleep/wake. The Core gained the first actions (`sendDirectText`, `sendChannelText`) and runs DM resends itself. Still to do: sim target at 320×240, a font with Polish/Cyrillic coverage, then screens by priority.
+5. **`ui-lvgl` skeleton** ✅ on L2 hardware (env `Wio_Tracker_L2_companion_solo_lvgl`, LVGL 9.2.2): status bar, home, conversation list, contact picker, conversation with keyboard, toasts, display sleep/wake. The Core gained the first actions (`sendDirectText`, `sendChannelText`) and runs DM resends itself. Then: European fonts + phone-style keyboard ✅, 320×240 sim target ✅. Next: screens by priority.
 6. Contacts/Nearby, Admin, Bot logic extraction as the LVGL screens for them are built.
 
 ## Decisions