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>

hardware/re-bba-rb/ftdi_eeprom.conf

@@ -0,0 +1,45 @@
+# FT2232H EEPROM config for the re-bba-rb board (libftdi `ftdi_eeprom`).
+#
+# NOTE: the devcontainer does NOT ship the `ftdi_eeprom` binary (debian's
+# libftdi1-2 is the runtime lib only). Inside the container program the EEPROM
+# with the pyftdi script instead — it applies the SAME values as this file:
+#     sudo /opt/venv/bin/python hardware/re-bba-rb/flash_ftdi_eeprom.py --commit
+# This .conf remains the value spec, and works as-is with `ftdi_eeprom` on a host
+# that has the libftdi tools, or as a reference when using FT_PROG on Windows.
+#
+# Purpose: give the on-board FT2232H a product string so the unit shows up as
+# "re-BBA-rb" instead of the generic "Dual RS232-HS".
+#
+# SAFE BY DESIGN — this KEEPS the stock VID/PID (0403:6010) and the default
+# dual-channel config, so `iceprog` (MPSSE on interface A) and the channel-B
+# UART keep working exactly as before.  Only the descriptor strings change.
+#
+# ⚠️ Before writing: back up whatever is there (it should be blank/default):
+#     ftdi_eeprom --device i:0x0403:0x6010 --read-eeprom --to-file eeprom-backup.bin
+#   Then flash the bitstream FIRST and confirm iceprog works; program this
+#   EEPROM only after that's proven (the string is cosmetic).
+#
+# Program with:
+#     ftdi_eeprom --device i:0x0403:0x6010 --flash-eeprom ftdi_eeprom.conf
+#   (re-plug the USB afterwards so the host re-reads the descriptors.)
+
+vendor_id=0x0403          # KEEP 0403 — iceprog/D2XX look for this
+product_id=0x6010         # KEEP 6010 — FT2232H default; iceprog looks for this
+max_power=500             # mA; board draws well under this over USB
+
+manufacturer=hashru       # <- your name/org; free text
+product=re-BBA-rb         # <- this is what makes it show as "re-BBA-rb"
+
+use_serial=true
+serial=RBBARB001          # <- optional; bump per unit if you want unique serials
+
+# Bus-powered while flashing over USB (GC not attached).  If you ever program
+# it while powered from SP1 only, this is still fine — it's a hint to the host.
+self_powered=false
+remote_wakeup=false
+
+# Leave the two channels at their FT2232H defaults (UART/serial).  MPSSE (used
+# by iceprog) is a runtime mode on interface A and works regardless, so there
+# is no need to set cha_type/chb_type here.
+
+filename=re-bba-rb-eeprom.bin   # ftdi_eeprom writes the built image here too