scaffold: Epic 1 — project scaffold

Add the full Rust + GTK4 + libadwaita project skeleton:
- Cargo.toml with all dependencies (gtk4 0.11, libadwaita 0.9,
  webkit6 0.6, reqwest, serde, tokio, libsecret)
- build.rs that compiles Blueprint .blp files and bundles a GResource
- data/ui/window.blp — AdwApplicationWindow with AdwNavigationSplitView,
  sidebar with refresh button/spinner and primary menu,
  content page with article menu
- data/resources.gresource.xml bundling UI, HTML, and CSS
- data/net.jeena.FeedTheMonkey.gschema.xml with all GSettings keys
- html/content.html and html/content.css (minimal placeholders)
- src/main.rs, src/app.rs — AdwApplication with APP_ID net.jeena.FeedTheMonkey
- src/window.rs — AdwApplicationWindow GObject subclass loading the
  Blueprint template and persisting window size in GSettings
- COPYING (GPL-3.0) restored from master

The app compiles and the binary is ready to open a blank window.

Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "feedthemonkey"
+version = "3.0.0"
+edition = "2021"
+
+[[bin]]
+name = "feedthemonkey"
+path = "src/main.rs"
+
+[dependencies]
+gtk4 = { version = "0.11", features = ["v4_14"] }
+libadwaita = { version = "0.9", features = ["v1_6"] }
+webkit6 = { version = "0.6" }
+gio = { version = "0.22" }
+glib = { version = "0.22" }
+reqwest = { version = "0.12", default-features = false, features = ["rustls-tls", "json"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+tokio = { version = "1", features = ["full"] }
+libsecret = { version = "0.9" }
+
+[build-dependencies]