fix: resolve ESP32-S3 runtime crash, match official esp-hal examples

Root causes found and fixed:
- USB OTG init stole the PHY from USB-Serial-JTAG (the only USB on V4)
- executor-thread feature conflicted with esp-hal-embassy's executor
- Linker flags needed -Wl, prefix for GCC-to-LD passthrough
- Missing exception-handler feature on esp-backtrace
- Missing alloc in build-std
- Missing LTO and codegen-units=1 in release profile
- Vext on V4 is active LOW (datasheet correct, Arduino lib was wrong)

Now matches the official esp-hal v0.22.0 examples exactly.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -359,8 +359,6 @@ dependencies = [
  "critical-section",
  "document-features",
  "embassy-executor-macros",
- "embassy-time-driver",
- "embassy-time-queue-driver",
 ]
 
 [[package]]