B2: TFT_eSPI config via build_flags - retire the out-of-repo setup headers #184

_{Recreated from Strycher/Field_Compass-archive#184 — originally opened by @Strycher on 2026-08-09. Credentials redacted where present.}

Epic: #154

Move TFT_eSPI configuration into platformio.ini build_flags, retiring the three files still living inside the Arduino libraries folder, outside git:

• User_Setup_Select.h (edited to point at the below)
• User_Setups/Setup_Field_Compass_ESP32S3_ST7789.h (the active setup - filename says ST7789, the panel is ST7796)
• User_Setup.h (edited, currently inactive)

These are the last un-vendored config files. Epic A eliminated the patched driver and lv_conf.h; this finishes the job. Until it lands, the only copies outside the live library sit in a backup folder on one machine.

Read the active setup header for the real values. Known: ST7796, 480x320, SPI 80MHz, MISO 37 / MOSI 35 / SCK 36 / CS 18 / DC 17 / RST 16.

Also add -D LV_CONF_INCLUDE_SIMPLE and -I include so include/lv_conf.h is served straight from the repo - that retires scripts/sync-lv-conf.py, which exists only as an arduino-cli bridge (#158).

Acceptance criteria

• pio run compiles with no TFT_eSPI project files in the Arduino libraries folder
• scripts/sync-lv-conf.py marked arduino-cli-only, or removed if arduino-cli is retired
• Rotation stays setRotation(3) (A1: replace ST7796 rotation patch with setRotation(3) #157) - do not reintroduce a patched driver