skill: add usb-sniffer — wire-level capture with the ataradov hardware tap

Fourth view in the USB debugging toolset (usbmon = host URBs, usb-debug =
host reasoning, usb-target-debug = device firmware, usb-sniffer = what
actually crossed D+/D-). Covers the ataradov/usb-sniffer analyzer:
headless pcapng capture (--speed ls/fs/hs, --fold, --limit self-exit),
Wireshark/tshark analysis recipes, and the wire realities that bite:
downstream broadcast, sniffer self-capture noise, xHCI devnum != wire
address, tap-point-dependent reset visibility (hub choreography anchors),
FS-behind-HS-hub splits. Every recipe hardware-validated on the rig,
including the capture-window floor (a 3 s window provably misses the
enumeration ladder; 3M packets minimum).

Two udev files with distinct audiences, not one:
- examples/device/99-tinyusb-examples.rules (renamed from 99-tinyusb.rules):
  the user-facing rules the examples need — cafe VID access, hidraw, the
  ModemManager blacklist, a couple of board probes. getting_started.rst,
  the webusb_serial README and its source comment point here.
- tools/88-tinyusb.rules: the HIL rig's private probe/analyzer allowlist,
  now with the sniffer (6666:6620 + blank FX2LP 04b4:8613). Installed on
  the rig only; the usb-sniffer skill references it.

3 files changed, 4 insertions, 3 deletions

diff --git a/examples/device/99-tinyusb.rules b/examples/device/99-tinyusb-examples.rules
index d306bada5..e7a399345 100644
--- a/examples/device/99-tinyusb.rules
+++ b/examples/device/99-tinyusb-examples.rules
@@ -1,5 +1,6 @@
+# udev rules for running the TinyUSB device examples as a non-root user.
 # Copy this file to the location of your distribution's udev rules, for example on Ubuntu:
-#   sudo cp 99-tinyusb.rules /etc/udev/rules.d/
+#   sudo cp 99-tinyusb-examples.rules /etc/udev/rules.d/
 # Then reload udev configuration by executing:
 #   sudo udevadm control --reload-rules
 #   sudo udevadm trigger
diff --git a/examples/device/webusb_serial/README.md b/examples/device/webusb_serial/README.md
index 5ca70f909..15837e59e 100644
--- a/examples/device/webusb_serial/README.md
+++ b/examples/device/webusb_serial/README.md
@@ -51,4 +51,4 @@ make BOARD=raspberry_pi_pico all
 
 After flashing, open the landing page (`https://example.tinyusb.org/webusb-serial/index.html`) in a WebUSB-capable browser such as Chrome, click **Connect**, and select the device — the on-board LED lights solid once connected. Characters typed in the web page are echoed back, and are also mirrored to the CDC serial port (e.g. `/dev/ttyACM0`) and vice versa.
 
-On Linux/macOS you may need to install the udev rules from `examples/device/99-tinyusb.rules` for the browser to access the device.
+On Linux/macOS you may need to install the udev rules from `examples/device/99-tinyusb-examples.rules` for the browser to access the device.
diff --git a/examples/device/webusb_serial/src/main.c b/examples/device/webusb_serial/src/main.c
index 4be5e4db4..e200c334c 100644
--- a/examples/device/webusb_serial/src/main.c
+++ b/examples/device/webusb_serial/src/main.c
@@ -39,7 +39,7 @@
  * is done automatically by firmware.
  *
  * - On Linux/macOS, udev permission may need to be updated by
- *   - copying '/examples/device/99-tinyusb.rules' file to /etc/udev/rules.d/ then
+ *   - copying 'examples/device/99-tinyusb-examples.rules' file to /etc/udev/rules.d/ then
  *   - run 'sudo udevadm control --reload-rules && sudo udevadm trigger'
  */