feat(tui): add vim-like keybinds and settings tab for config edit

yarr.toml.example

@@ -6,15 +6,36 @@
 [sonarr]
 # Sonarr server URL (required)
 # Example: "http://localhost:8989" or "https://sonarr.example.com"
+# Can also be edited from the Settings tab in the application
 url = "http://localhost:8989"
 
 # Sonarr API key (required)
 # You can find this in Sonarr under Settings > General > Security > API Key
+# Can also be edited from the Settings tab in the application
 api_key = "your-api-key-here"
 
+[ui]
+# Keybind mode: "Normal" or "Vim"
+# Normal mode uses standard navigation keys (arrows, j/k)
+# Vim mode uses vim-like keybinds (hjkl, gg, G, etc.)
+# Can be toggled from the Settings tab in the application
+keybind_mode = "Normal"
+
+# Show help text in the footer
+# Can be toggled from the Settings tab in the application
+show_help = true
+
+# All settings can be changed in the Settings tab:
+# 1. Launch yarr and navigate to the Settings tab (last tab)
+# 2. Use arrow keys to select a setting
+# 3. Press Enter to edit Sonarr URL/API key or toggle other options
+# 4. Press 's' to save changes
+
 # Environment variables can also be used:
 # YARR_SONARR_URL="http://localhost:8989"
 # YARR_SONARR_API_KEY="your-api-key-here"
+# YARR_UI_KEYBIND_MODE="Vim"
+# YARR_UI_SHOW_HELP="false"
 #
 # Command line arguments take highest priority:
 # yarr --sonarr-url="http://localhost:8989" --sonarr-api-key="your-key"