refactor: remove box border from config example for easier copy-paste

The fancy box border (┌─┐│└┘) around the configuration example made it
difficult to copy-paste into the config file. Users had to manually remove
the vertical line characters from each line.

Changes:
- Removed box border characters (┌, ─, ┐, │, └, ┘)
- Kept the same indentation and formatting
- Added "(copy-paste ready)" note to clarify it can be directly pasted
- Maintains visual structure with proper spacing

The configuration example is now directly copy-pasteable into the Reticulum
config file without any manual editing required.

Before:
   ┌─────────────────────────────────────────┐
   │ [[BLE Interface]]                       │
   │   type = BLEInterface                   │
   ...

After:
   [[BLE Interface]]
     type = BLEInterface
     enabled = yes
   ...

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

install.sh

@@ -628,16 +628,15 @@ echo
 echo "1. Add the BLE interface to your Reticulum config:"
 echo "   File: $CONFIG_FILE"
 echo
-echo "   Add this section:"
-echo "   ┌─────────────────────────────────────────┐"
-echo "   │ [[BLE Interface]]                       │"
-echo "   │   type = BLEInterface                   │"
-echo "   │   enabled = yes                         │"
-echo "   │                                         │"
-echo "   │   # Enable both modes for mesh          │"
-echo "   │   enable_peripheral = yes               │"
-echo "   │   enable_central = yes                  │"
-echo "   └─────────────────────────────────────────┘"
+echo "   Add this section (copy-paste ready):"
+echo
+echo "   [[BLE Interface]]"
+echo "     type = BLEInterface"
+echo "     enabled = yes"
+echo
+echo "     # Enable both modes for mesh"
+echo "     enable_peripheral = yes"
+echo "     enable_central = yes"
 echo
 echo "2. See examples/config_example.toml for all configuration options"
 echo