refactor(swap): rename imported .md files to md- prefix for swap mechanism

Restore the canary file naming convention that swap_sources.py expects:
the imported MyST pages now live as docs/<dir>/md-<name>.md alongside
the existing docs/<dir>/<name>.rst, so swap_sources.py --swap can rename
them into place at build time.

- 254 .md files renamed (every page with a matching .rst counterpart)
- 2 MyST-only pages left at their final names (no .rst exists, no swap
  needed): docs/copyright.md, docs/automation/terraform/terraformvyos.md

All 114 stems listed in docs/_swap.txt now have a corresponding
md-<name>.md source file ready to swap in.

🤖 Generated by [robots](https://vyos.io)

1 files changed, 0 insertions, 148 deletions

diff --git a/docs/vpp/configuration/interfaces/loopback.md b/docs/vpp/configuration/interfaces/loopback.md
deleted file mode 100644
index 844892a3..00000000
--- a/docs/vpp/configuration/interfaces/loopback.md
+++ /dev/null
@@ -1,148 +0,0 @@
----
-lastproofread: '2026-03-13'
----
-
-(vpp-config-interfaces-loopback)=
-
-```{include} /_include/need_improvement.txt
-```
-
-
-# VPP Loopback Interface Configuration
-
-VPP loopback interfaces provide virtual interfaces that remain
-administratively up and are commonly used for stable addressing,
-routing protocols, and as Bridge Virtual Interfaces (BVI). Loopback
-interfaces in VPP offer high-performance virtual connectivity with optimized
-packet processing.
-
-## Basic Configuration
-
-### Creating a Loopback Interface
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\>
-
-Create a loopback interface where ``<vpploN>`` follows the naming
-convention ``vpplo1``, ``vpplo2``, etc.
-```
-
-**Basic Example:**
-
-```none
-set interfaces vpp loopback vpplo1
-```
-
-## Interface Configuration
-### Description and Administrative Control
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\> description \<description\>
-
-Set a descriptive name for the loopback interface.
-```
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\> disable
-
-Administratively disable the loopback interface.
-```
-
-### Kernel Interface Integration
-
-Kernel interface is bound to the VPP loopback interface for management
-and application compatibility.
-
-## IP Address Configuration
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\> address \<ip-address/prefix\>
-
-Configure IPv4 or IPv6 addresses on the kernel interface. Multiple
-addresses can be assigned.
-```
-
-**Examples:**
-
-```none
-# IPv4 address
-set interfaces vpp loopback vpplo1 address 192.168.1.10/24
-
-# IPv6 address
-set interfaces vpp loopback vpplo1 address 2001:db8::10/64
-```
-
-## MTU Configuration
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\> mtu \<size\>
-
-Set the Maximum Transmission Unit (MTU) for the kernel interface.
-The MTU must be compatible with the connected VPP interface.
-```
-
-## VLAN Configuration
-
-VPP kernel interfaces support VLAN (Virtual LAN) sub-interfaces for network
-segmentation.
-
-### Creating VLAN Sub-interfaces
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\> vif \<vlan-id\>
-
-Create a VLAN sub-interface with the specified VLAN ID (0-4094).
-```
-
-### VLAN Sub-interface Configuration
-
-VLAN sub-interfaces support the same configuration options as the parent
-interface:
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\> vif \<vlan-id\> address \<ip-address/prefix\>
-```
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\> vif \<vlan-id\> description \<description\>
-```
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\> vif \<vlan-id\> disable
-```
-
-```{cfgcmd} set interfaces vpp loopback \<vpploN\> vif \<vlan-id\> mtu \<size\>
-```
-
-**Examples:**
-
-```none
-# Configure VLAN 100
-set interfaces vpp loopback vpplo1 vif 100 address 192.168.100.1/24
-set interfaces vpp loopback vpplo1 vif 100 description "Management VLAN"
-set interfaces vpp loopback vpplo1 vif 100 mtu 1500
-
-# Configure VLAN 200
-set interfaces vpp loopback vpplo1 vif 200 address 192.168.200.1/24
-set interfaces vpp loopback vpplo1 vif 200 description "Guest VLAN"
-```
-
-## Configuration Examples
-### Basic Loopback Interface
-
-```none
-# Create simple loopback
-set interfaces vpp loopback vpplo1
-set interfaces vpp loopback vpplo1 description "Router ID interface"
-```
-
-### Loopback with Kernel Interface
-
-```none
-# Loopback with management access
-set interfaces vpp loopback vpplo2
-set interfaces vpp loopback vpplo2 description "Management loopback"
-set interfaces vpp loopback vpplo2 address 10.255.255.1/32
-```
-
-### Bridge Virtual Interface (BVI)
-
-```none
-# Loopback as BVI for bridge
-set interfaces vpp loopback vpplo3
-set interfaces vpp loopback vpplo3 description "Bridge gateway interface"
-set interfaces vpp bridge vppbr1
-set interfaces vpp bridge vppbr1 member interface vpplo3 bvi
-set interfaces vpp loopback vpplo3 address 192.168.100.1/24
-```