USB open: Kestrel skips the reset; reopen recovery + bounded topology discovery (#294)

[josephnef]

Fixes the mechanical half of #294 (the deafness half was the RX-descriptor walk fix already merged in #295 — full root-cause analysis in the issue comment).

Problem

libusb_reset_device on a Kestrel with running (or SIGKILL-orphaned) firmware crashes it to bootrom: the device re-enumerates (device firmware changed), the open dies with a stale handle, and the ROM path can land in the dead ZeroCD DISK id (0bda:1a2b — bInterfaceNumber 255, unclaimable by libusb and kernel usbfs, so no userspace eject exists; only a VBUS power-cycle recovers). Any harness cycling the demos hit retry roulette; every zero read looked like a deaf receiver.

Fix

• claim_interface_then_reset skips the USB reset for any kestrel::variant_for_usb_id match. Kestrel power_on forces the MAC off from any retained state — the reset added nothing but the ROM-drop risk. Covers all demos at once. Bench: SIGKILL-churn 6/6 clean without the reset vs ZeroCD roulette with it.
• New devourer::claim_interface_reset_reopen (used by rxdemo/txdemo/streamtx): when a reset does re-enumerate (other chips / forced), close the stale handle, wait bounded for the same bus+port to return under the original VID:PID (transient ZeroCD ids are not a match), re-open and re-claim without a second reset — the re-enumeration itself reloaded the firmware.
• Bounded topology discovery: with DEVOURER_USB_BUS/PORT set, the demos poll the named socket for up to 15 s instead of failing on the first empty scan (a closed/killed predecessor leaves the chip re-enumerating for seconds). Strict no-fall-through behavior unchanged.
• Selftest: locks the issue-Kestrel (8852BU/8832CU): bimodal deaf RX bring-up — loop starts green, 0 frames until VBUS cold (sometimes) #294 aggregate-walk regression — [PPDU_STS(drv_info, unit 16)][WIFI]: the trailing WIFI frame must be reached (with the old offset formula the walk broke after the phy-status sub-packet → green bring-up, zero frames).

Validation

• SIGKILL-churn ×6 on the 8832CU, default env: 6/6 bring-ups deliver (700–1000 frames/15 s), 0 ZeroCD landings, 0 stale handles — vs 5/6 failing before.
• From VBUS cold: clean.
• tests/he_er_su_cross_rx.sh same-die (8852C→8852C) and cross-die (8852B→8852C), ch6: 8/8 cells pass on the first attempt, zero retries, zero VBUS cycles — vs all-day retry roulette.
• 24/24 ctest.

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