fix(config): add template keys the code already reads

display.hardware gains pixel_mapper_config, row_address_type,
multiplexing and panel_type (read at display_manager.py with these exact
fallbacks — users on non-standard panels previously had no way to
discover them from the template). vegas_scroll gains
frame_based_scrolling and scroll_delay, the only two of its 27 keys the
template omitted (read in src/vegas_mode/config.py). plugin_system gains
development_mode, which the web UI reads and writes but the template
never declared.

Every added value is byte-identical to the code-side .get() fallback, so
ConfigManager._migrate_config() merging these keys into existing user
configs cannot change behavior on any installed device.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SXb4mKcAkVaxkeTb3YnAdr

config/config.template.json

@@ -110,7 +110,11 @@
             "inverse_colors": false,
             "show_refresh_rate": false,
             "led_rgb_sequence": "RGB",
-            "limit_refresh_rate_hz": 100
+            "limit_refresh_rate_hz": 100,
+            "pixel_mapper_config": "",
+            "row_address_type": 0,
+            "multiplexing": 0,
+            "panel_type": ""
         },
         "runtime": {
             "gpio_slowdown": 3,
@@ -149,7 +153,9 @@
             "overflow_mode": "rotate",
             "dynamic_duration_enabled": true,
             "min_cycle_duration": 60,
-            "max_cycle_duration": 240
+            "max_cycle_duration": 240,
+            "frame_based_scrolling": true,
+            "scroll_delay": 0.02
         }
     },
     "sync": {
@@ -160,7 +166,8 @@
     "plugin_system": {
         "plugins_directory": "plugin-repos",
         "auto_discover": true,
-        "auto_load_enabled": true
+        "auto_load_enabled": true,
+        "development_mode": false
     },
     "web-ui-info": {
         "enabled": true,