Build the screens with ESPHome 2026.9 and keep its build memory in the app's own storage, give the CYD 94 KB more room, and stop a timer from counting one second too many (0.2.89)

The add-on ships ESPHome 2026.9.0: it builds an ESP32 with ESP-IDF itself
and keeps a compiler cache. firmware.py gives the CLI its own storage in
/data (ESPHOME_DATA_DIR /data/esphome, which the ESPHome Device Builder no
longer wipes on start; ESP-IDF and ccache in /data/idf, at most 1 GB;
compilers limited to the core count as PlatformIO ran them), removes the
unused PlatformIO once before the first ESP-IDF build, and leaves the new
folders out of backups.

Firmware 0.2.75: assertion_level SILENT in every board's esp32 block, the
core logs from INFO, and clock_parts() in runtime_model.h replaces sscanf.
timer_left() caps a running timer at its duration (the screen's clock runs
up to a second behind Home Assistant's). The packages keep min_version
2026.6.2, the top-level online_image and OTA passwords for new screens, so
an add-on or Device Builder that isn't updated yet keeps building every
screen; CI now builds both boards with the add-on's ESPHome and with
min_version. ESP-IDF's error names stay on, and build_flags stay under
platformio_options, because ESPHome 2026.9's LVGL reads only those.

tools/check.sh: 478 Python tests, 19/19 C++, editor; --firmware PASS with
ESPHome 2026.6.2 (CYD 87.7 %), 2026.8.1 (88.3 %) and 2026.9.0 (86.4 %,
was 91.5 %). Both bench screens OTA'd and watched for half an hour;
ESP Screens as a local add-on on the Yellow built both profiles
(CYD 1,037 s first build, 41 s unchanged). Details:
docs/TEST_RESULTS_0289.md.

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

docs/PROFILES.md

@@ -37,7 +37,9 @@ the board file replaces the core's. `esphome config home-like-2432s028.yaml` sho
 ## Adding a board
 
 1. Copy the board file of the panel that resembles the new one most (a small SPI panel: the CYD; a big RGB panel
-   with capacitive touch: the Guition) to `packages/boards/<board>.yaml` and change its hardware sections.
+   with capacitive touch: the Guition) to `packages/boards/<board>.yaml` and change its hardware sections. Keep
+   `assertion_level: SILENT` in its `esp32:` block (firmware 0.2.75+): every board builds its firmware the same way,
+   and `tests/test_easy_package.py` checks it.
 2. Fill the sizes table for the new resolution, and go through the hooks: keep, change or empty each one.
 3. Add `packages/<board>.yaml` and `<board>.yaml` after the existing entries, `<board>` to `ENTRIES` in
    `tools/profiles.py` and to `REFS` in `screen_manager/app/core.py` (the boards `installation_yaml()` writes a