Introduce initial implementation of the vmic CLI with PipeWire integration

- Added `Cargo.toml` to define dependencies and project metadata.
- Implemented core CLI functionality for managing virtual microphones (`create`, `edit`, `delete`, `list`, `route`, and `wipe` commands) using `clap`.
- Integrated `rusqlite` for persistent state storage and `pipewire` to manage PipeWire nodes.
- Ensured graceful handling of feedback loops and system defaults during virtual mic creation and deletion.
- Added error handling via `thiserror` for cleaner error definitions.

src/commands/delete.rs

@@ -0,0 +1,31 @@
+use crate::cli::DeleteArgs;
+use crate::error::Result;
+use crate::pw::{loopback, PwGraph};
+use crate::state::{self, VmicState};
+use crate::ui;
+
+pub fn run(args: DeleteArgs) -> Result<()> {
+    let conn = state::open_db()?;
+    let name = state::normalize(&args.name);
+    let mut state = VmicState::load(&conn, &name)?;
+    let graph = PwGraph::connect()?;
+
+    if let Some(loopback_id) = state.loopback_id {
+        loopback::unload_pulse_module(loopback_id)?;
+    }
+
+    // Unlink a mixed-in hardware source explicitly; the links would also
+    // die with the nodes below.
+    super::unsource(&graph, &mut state)?;
+
+    if let Some(pid) = state.mix_pid {
+        loopback::terminate_stage(pid, &state.mix_name)?;
+    }
+    if let Some(pid) = state.sink_pid {
+        loopback::terminate_stage(pid, &state.sink_name)?;
+    }
+
+    VmicState::delete(&conn, &name)?;
+    ui::ok(&format!("Deleted virtual mic '{name}'."));
+    Ok(())
+}