feat: implement notification sound functionality with user customization options

docs/changelog/v0.2.3.md

@@ -1,4 +1,4 @@
-# v0.2.3 - Moderation, Private Channels & UI Overhaul
+# v0.2.3 - Moderation, Embeds & UI Overhaul
 
 ## Features
 
@@ -16,6 +16,21 @@
 - `GET /api/channels` returns the combined list: public channels + user's joined private channels
 - Channel creators are automatically added as members
 
+### OpenGraph Link Embeds
+- Messages containing URLs now show a rich preview below the message text
+- Server-side fetching: detects the first URL in a message, fetches the page, and parses OpenGraph meta tags (`og:title`, `og:description`, `og:image`, `og:site_name`)
+- OG images are converted to a small 24x12 colored ASCII thumbnail using the existing half-block renderer
+- Embeds are persisted in the database and included in channel history
+- TUI client renders embeds with a `▏` left border bar — site name and border in blue, title in white, description in gray, followed by the ASCII thumbnail
+- IRC gateway receives a text-only embed preview (site name, title, description) — no ASCII thumbnail to keep IRC output clean
+- Falls back to `<title>` tag when no OG tags are present; gracefully skips if no useful metadata is found
+- 3-second fetch timeout ensures message delivery is never significantly delayed
+- SSRF protection rejects private/loopback IP addresses before fetching
+
+### Notification Sounds
+- Incoming messages play a notification sound when the terminal is not focused
+- Embedded MP3 asset with cross-platform playback support
+
 ### Online Users Panel
 - Collapsible right-side panel showing online users in the current channel (toggle with F2)
 - Users displayed with status indicators, role badges, and their custom nickname colors
@@ -36,6 +51,7 @@
 - Version number shown in the status bar
 - Custom colored rendering for channel list (active indicator, unread count badges)
 - Avatar upload field added to the profile edit dialog (file path or URL)
+- Profile avatar now renders with full color tag support in the profile view dialog
 - Update check notification on connect — shows a system message if a newer GitHub release exists
 - Chat messages no longer show selection/focus highlight
 - Exit shortcut changed from Ctrl+C to Alt+Q — frees Ctrl+C for copy
@@ -48,12 +64,19 @@
 - Wired `OnChannelUpdated` SignalR event so new public channels appear for all connected users in real time
 - Fixed color tag parser using wrong regex group numbers (6,7,8 instead of 1,2,3) — new ASCII art was rendering without colors
 - Full Unicode/emoji support — renderers use Terminal.Gui v2 grapheme cluster API (`GraphemeHelper`, `AddStr`) for proper wide character handling
+- Emoji-to-text shortcode conversion for consistent cross-platform rendering
 - Fixed `/send` and `/avatar` commands not handling file paths with spaces correctly, even when quoted
-- Profile avatar now renders with full color tag support instead of showing raw tags
 - Server-side newline spam protection — consecutive blank/whitespace-only lines collapsed to 1 and total lines capped at 30
 
 ## Infrastructure
 
+- New `LinkEmbedService` on the server — URL detection, HTML fetching (first 64KB), OG tag parsing via regex, image thumbnail generation
+- `EmbedDto` record added to shared Core DTOs; `MessageDto` extended with optional `Embed` field (backward-compatible)
+- `EmbedJson` nullable column on the `Message` table stores serialized embed data (max 8KB)
+- Dedicated `"OgFetch"` named HttpClient with bot User-Agent header and 5-second timeout
+- `NotificationSoundService` for cross-platform audio playback of embedded notification sounds
 - Startup `DataMigrationService` automatically converts old ANSI-format messages to the new color tag format on server boot, logging the count of migrated records
-- Three new EF Core migrations: `AddModerationRoles`, `AddChannelIsPublic`, `AddChannelMembership`
+- `EmojiHelper` utility for emoji-to-shortcode conversion
+- Heartbeat handling in `ServerDirectoryService` for connection health checks
+- Four new EF Core migrations: `AddModerationRoles`, `AddChannelIsPublic`, `AddChannelMembership`, `AddMessageEmbed`
 - `ChannelMembership` table with cascade delete on both channel and user removal