Add hex color parsing helper and implement custom list sources for channels and users

- Introduced HexColorHelper for parsing hex color strings to Terminal.Gui Attributes and Colors.
- Created ChannelListSource for managing and rendering a list of channels with unread counts and active indicators.
- Developed UserListSource for displaying online users with per-user nickname colors.
- Refactored MainWindow to utilize ChatMessageManager for handling messages and channel state.
- Updated project references and removed unused content from the server project.
- Adjusted tests to reflect changes in namespaces and structure.

docs/changelog/v0.2.5.md

@@ -102,6 +102,7 @@
 ### EchoHub Branding
 
 - Status bar "EchoHub" text now uses golden color (218, 165, 32)
+- Extracted `ChatMessageManager` from `MainWindow` — message storage, formatting, and mutation logic now in a dedicated class, reducing MainWindow complexity
 
 ## Infrastructure
 

docs/changelog/v0.2.6.md

@@ -0,0 +1,20 @@
+# v0.2.6
+
+## Refactoring
+
+- Extracted `ChatMessageManager` from `MainWindow` — message storage, formatting, and mutation logic now in a dedicated class, reducing MainWindow complexity
+- Split `ChatRenderer.cs` (8 classes, 548 lines) into 7 individual files: `ChatSegment`, `ChatLine`, `ChatListSource`, `ChannelListSource`, `UserListSource`, `ChatColors`, `ColorHelper`, `RenderHelpers`
+- Extracted `ConnectionManager` from `AppOrchestrator` — connection lifecycle, authentication, SignalR event wiring, and channel tracking now in a dedicated service
+- Extracted `AvatarHelper` — deduplicated avatar upload logic previously duplicated in `/avatar` command and profile edit dialog
+- Consolidated `ProfileEditDialog.ParseHexToTrueColor` into shared `ColorHelper.ParseHexToColor`
+- Extracted `UserSession` — session state (`Username`, `Status`, `StatusMessage`) now in a dedicated class instead of scattered fields
+- Replaced 21 inline command handler lambdas with named `HandleCmd*` methods for improved readability
+- Extracted shared `CleanupConnectionAsync` to deduplicate disconnect/logout cleanup logic
+- Reorganized flat `UI/` folder (19 files) into subfolders: `Chat/`, `Dialogs/`, `ListSources/`, `Helpers/` with matching namespaces
+- Moved `AsyncRunner` from project root to `Services/` with updated namespace
+- Renamed `ColorHelper` → `HexColorHelper` to avoid namespace collision with Terminal.Gui's `ColorHelper` NuGet dependency
+- Moved `hue_icon.ico` to `Client/Assets/`, removed duplicate from Server (Server now references shared icon via relative path)
+
+## Infrastructure
+
+- Release workflow: use `--notes-file` instead of inline `--notes` interpolation to prevent shell expansion of special characters in commit messages