host: review fixes for cargo.build, the test runner, the console, and main; tests for every PROTOCOL.md rule

cargo.build and the runner (review T22R): builds use the network again;
core.unlock and core.notify in order under the runner; quiet test
output; manifest preparation keeps [workspace], target tables, renamed
and optional entries; cargo.rpc.discover; -32004 with data.output;
retention of 10 builds; light, empty test worlds with an in-memory
journal; only CARGO_/RUST_/SAUSAGE_ variables; stdin is null; the runner
through --config. A compile cache that cannot be created is not fatal.
Activation replaces plugin.wasm without a gap.

Console and main: init ships the workspace Cargo.lock and creates the
world atomically; each console command runs in its own task, so ps,
stop, and kill work during a slow call; SAUSAGE_HEADLESS; the terminal
mode is restored; signals during boot; chat text is not taken as a
command.

Tests: 20 more tests for PROTOCOL.md sections 2 to 10; the cargo tests
choose the libtest binary from cargo's JSON output and time out.

cli/src/host.rs

@@ -65,7 +65,25 @@ impl Host {
         .await??;
         let journal =
             journal::Journal::open(world.state_dir("core").join("journal.sqlite")).await?;
-        let host = Self(Arc::new(Inner {
+        let host = Self::with_parts(world, runtime, journal);
+        let cargo_world = host.0.world.clone();
+        let cargo =
+            tokio::task::spawn_blocking(move || crate::cargo::Cargo::new(cargo_world)).await??;
+        cargo.register(&host);
+        host.boot().await?;
+        Ok(host)
+    }
+    /// Creates an empty test world with a shared engine and an in-memory journal.
+    pub async fn test_world(path: &Path, runtime: Arc<Runtime>) -> anyhow::Result<Self> {
+        std::fs::create_dir_all(path)?;
+        Ok(Self::with_parts(
+            World::open(path)?,
+            runtime,
+            journal::Journal::memory().await?,
+        ))
+    }
+    fn with_parts(world: World, runtime: Arc<Runtime>, journal: journal::Journal) -> Self {
+        Self(Arc::new(Inner {
             world,
             runtime,
             journal: Arc::new(journal),
@@ -85,13 +103,7 @@ impl Host {
             activations: tokio::sync::Mutex::new(()),
             watcher: Mutex::new(None),
             retirements: Mutex::new(std::collections::HashSet::new()),
-        }));
-        let cargo_world = host.0.world.clone();
-        let cargo =
-            tokio::task::spawn_blocking(move || crate::cargo::Cargo::new(cargo_world)).await??;
-        cargo.register(&host);
-        host.boot().await?;
-        Ok(host)
+        }))
     }
     /// Register a native plugin for subsequent calls.
     pub fn register_native(&self, name: &str, plugin: NativePlugin) {