Enable in-container USB flashing + flash-re-bba-rb skill; find U7 EEPROM undersized

Devcontainer now grants libusb access to the FT2232H so iceprog (bitstream) and
pyftdi (FT2232H EEPROM) run inside the container:
- devcontainer.json: --privileged + /dev/bus/usb bind mount
- Dockerfile: sudo (NOPASSWD for vscode; USB nodes are root-owned), libusb-1.0-0,
  libftdi1-2, pyftdi

Add the flash-re-bba-rb skill documenting the procedure (bitstream via best swept
seed, optional EEPROM string, troubleshooting, guardrails) and
flash_ftdi_eeprom.py (pyftdi, backup-first, dry-run default) + ftdi_eeprom.conf
value spec.

Bring-up on the repaired V1 unit: bitstream flash VERIFY OK (iceprog
build/seed4/top.bin, capture 58.36 MHz). EEPROM product string CANNOT be
programmed on V1 — U7 is a 93LC46B (128 B), too small for the FT2232H, which
needs a 93LC56B (256 B); the 128 B chip mirrors and the config write fails
verify. This overturns the old REVIEW note "93LC46B = correct for FT2232H"
(that only checked ORG, not size). Board still works blank -> ROM defaults;
iceprog + UART unaffected. Documented in REVIEW.md + TODO.md (swap U7->93LC56B
for V2); flash_ftdi_eeprom.py detects the mirroring and refuses the write.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -22,7 +22,12 @@ W5500 ethernet back-end".
 **Windows host + WSL2 devcontainer — USB flashing setup:**
 1. Install `usbipd-win` (https://github.com/dorssel/usbipd-win/releases)
 2. Run `.devcontainer/attach-icebreaker.ps1` as Administrator before opening the devcontainer
-3. The devcontainer runs `--privileged` to pass through the USB device
+3. The devcontainer runs `--privileged` AND bind-mounts `/dev/bus/usb` so libusb
+   (`iceprog`, `pyftdi`) can see the FT2232H; the `vscode` user flashes via
+   passwordless `sudo` (the USB nodes are root-owned). If you change
+   `.devcontainer/`, **rebuild the container** for it to take effect.
+4. Flashing the re-bba-rb board (bitstream + FT2232H EEPROM) is documented as the
+   `flash-re-bba-rb` skill — see `.claude/skills/flash-re-bba-rb/SKILL.md`.
 
 **Local venv (outside devcontainer):**
 ```bash