Initial braindump app implementation

Create a complete braindump note-taking application with Dioxus 0.7 featuring:
- Note capture with title, content, and tags
- Full CRUD operations (create, read, update, delete)
- Search functionality for notes
- Tag-based filtering
- Note pinning for quick access
- Modern dark theme with purple accents
- Responsive sidebar layout
- Clean card-based note list
- Full-text editor with auto-save hint

Implemented with:
- Dioxus 0.7.1 fullstack for reactive UI and server functions
- Workspace pattern with shared API crate
- In-memory storage using LazyLock
- Server functions for note management

All core features working and ready for testing.

Cargo.toml

@@ -0,0 +1,19 @@
+[workspace]
+resolver = "2"
+members = [
+    "packages/ui",
+    "packages/web",
+    "packages/desktop",
+    "packages/mobile",
+    "packages/api",
+]
+
+[workspace.dependencies]
+dioxus = { version = "0.7.1" }
+serde = { version = "1.0", features = ["derive"] }
+chrono = { version = "0.4", features = ["serde"] }
+uuid = { version = "1.0", features = ["v4", "serde"] }
+
+# workspace
+ui = { path = "packages/ui" }
+api = { path = "packages/api" }