Restructure docs: archive VLAN migration, update IPs to VLAN 10

Major documentation cleanup after VLAN migration completion:
- Archive 12 VLAN project docs to archive/vlan-migration/
- Archive 5 done WIP docs (VLAN proposals, AI stack, Fossorial, DNS backup)
- Create standing reference docs 08-DNS-ARCHITECTURE and 09-TAILSCALE-VPN
- Renumber docs to clean 01-09 sequence with merged CHANGELOG
- Update all active docs from stale 192.168.31.x to current VLAN 10 IPs
- Fix CSS1 (.10.9→.10.3) and ZX1 (.10.7→.10.4) IPs in hardware inventory
- Clean 06-VLAN-DEVICE-ASSIGNMENT: remove migration columns/sections, fix VLAN 25 subnet

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/04-HARDWARE-INVENTORY.md

@@ -36,12 +36,12 @@
 |----------|-------|
 | **Role** | Distribution Switch |
 | **Location** | 19" Rack U1 |
-| **IP** | 192.168.10.9 |
+| **IP** | 192.168.10.3 |
 | **MAC** | F4:1E:57:C9:BD:09 |
 | **OS** | SwOS 2.16 |
 | **Serial** | - |
 | **Docs** | https://help.mikrotik.com/docs/spaces/UM/pages/17498168/CSS326-24G-2S+RM |
-| **Web UI** | http://192.168.10.9 |
+| **Web UI** | http://192.168.10.3 |
 
 **Ports:** 24x 1G RJ45, 2x 10G SFP+
 - SFP1: 10G DAC to ZX1
@@ -55,7 +55,7 @@
 |----------|-------|
 | **Role** | Core Switch (2.5GbE) |
 | **Location** | 10" Rack U7 (on shelf) |
-| **IP** | 192.168.10.7 |
+| **IP** | 192.168.10.4 |
 | **MAC** | 1C:2A:A3:1E:78:67 |
 | **Serial** | - |