loopTask: cv_init() created a CVState{} temporary (9KB background
array) on the stack — fixed by initializing members directly.
cam task: cv_process() had uint8_t fg[CV_PIXELS] (9KB) as a local
variable — made static, matching the existing fg_copy fix.
cam task stack bumped from 4096 to 8192 for headroom.
Also: switch to 4MB OTA partition table (TimerCamera-F has 4MB flash,
not 8MB), add CONFIG_ARDUINO_LOOP_STACK_SIZE=16384 build flag,
upload_speed=115200 and --no-stub for reliable CH340 flashing.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
