Release v0.2.0: Task comments, recurring calendar, system tray, app branding

New features:
- Task comments with date-stamped entries and last-comment summary
- Recurring tasks expanded on calendar (daily/weekly/monthly/yearly)
- System tray mode replacing CMD window (Windows/macOS/Linux)
- Ironpad logo as exe icon, tray icon, favicon, and header logo

Technical changes:
- Backend restructured for dual-mode: dev (API-only) / prod (tray + server)
- tray-item crate for cross-platform tray, winresource for icon embedding
- Calendar view refactored with CalendarEntry interface for recurring merging
- Added CHANGELOG.md, build-local.ps1, version bumped to 0.2.0

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ironpad"
-version = "0.1.0"
+version = "0.2.0"
 edition = "2021"
 
 [dependencies]
@@ -46,4 +46,15 @@ uuid = { version = "1.0", features = ["v4"] }
 
 # Utilities
 lazy_static = "1.4"
-tokio-util = { version = "0.7", features = ["io"] }
+tokio-util = { version = "0.7", features = ["io"] }
+
+# System tray (production mode)
+tray-item = "0.10"
+
+# Windows icon loading (for tray icon)
+[target.'cfg(target_os = "windows")'.dependencies]
+windows-sys = { version = "0.52", features = ["Win32_UI_WindowsAndMessaging", "Win32_System_LibraryLoader"] }
+
+# Build dependencies (Windows icon embedding)
+[target.'cfg(target_os = "windows")'.build-dependencies]
+winresource = "0.1"