chore: scaffold tvctl foundation

Set up the Rust crate, baseline module layout, and project docs so the
repository matches the design bundle and builds cleanly as a starting point.

src/daemon/registry.rs

@@ -0,0 +1,8 @@
+use crate::adapters::Device;
+
+/// The persisted collection of known devices.
+#[derive(Debug, Clone, Default)]
+pub struct DeviceRegistry {
+    /// All devices currently remembered by the daemon.
+    pub devices: Vec<Device>,
+}