docs: replace real MAC addresses in examples with placeholders

The maintainer's two test-speaker MACs (A81B6A536A98 / A81B6A849D99,
plus colon-separated forms) appeared throughout documentation, runbooks,
and example READMEs. Public repo — same hygiene argument as the LAN-IP
sweep in 787c4fa.

Mapping:
  A81B6A536A98          → AABBCCDDEEFF
  A81B6A849D99          → AABBCCDDEE01
  A8:1B:6A:53:6A:98     → AA:BB:CC:DD:EE:FF
  A8:1B:6A:84:9D:99     → AA:BB:CC:DD:EE:01

The placeholders use the IANA-reserved AA:BB:CC:DD:EE:FF address that's
clearly synthetic, matching the convention the earlier anonymisation
pass had already adopted. 13 .md files touched; no tests, no code.

ANONYMIZATION-SUMMARY.md left for a dedicated rewrite commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/analysis/SETUP-WEBSOCKET-EXPERIMENT.md

@@ -178,7 +178,7 @@ One row per device tested. Once two devices on different firmware confirm the sa
 
 - Date: 2026-05-13
 - Firmware: 27.0.6.46330.5043500 (build epdbuild.trunk.hepdswbld04.2022-08-04T11:20:29)
-- Model: SoundTouch 10 (deviceID A81B6A536A98)
+- Model: SoundTouch 10 (deviceID AABBCCDDEEFF)
 - Bare setMargeAccount accepted: **yes** — pre-/info margeAccountUUID="" → post-/info margeAccountUUID="1111111"
 - Persistence written: **yes** — device materialized 14-entry Sources.xml on its own
 - Survives reboot: **yes** — `setup inspect` after `setup reboot` shows margeAccountUUID still 1111111

docs/analysis/SUPPORTED-URLS.md

@@ -6,7 +6,7 @@ This document provides a comprehensive analysis of the `/supportedURLs` endpoint
 
 **Test Devices:**
 - Device 1: `192.0.2.11:8090` (deviceID: `08DF1F0BA325`)
-- Device 2: `192.0.2.10:8090` (deviceID: `A81B6A536A98`)
+- Device 2: `192.0.2.10:8090` (deviceID: `AABBCCDDEEFF`)
 
 **Key Findings:**
 - Both devices return identical endpoint lists