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/tests/plugins/activation/src/main.rs

@@ -6,6 +6,38 @@ fn send(value: Value) {
     println!("{value}");
     io::stdout().flush().unwrap();
 }
+/// Calls a provider after activation releases an old consumer process.
+fn deferred(request: &Value, plugin: &str, lines: &mut impl Iterator<Item = io::Result<String>>) {
+    send(
+        json!({"jsonrpc":"2.0","id":request["id"],"result":std::env::var("SAUSAGE_PID").unwrap()}),
+    );
+    while !std::path::Path::new(&format!("/state/{plugin}/release-call")).exists() {
+        std::thread::sleep(std::time::Duration::from_millis(1));
+    }
+    send(json!({"jsonrpc":"2.0","id":"deferred","method":"notes.legacy","params":{}}));
+    for line in lines {
+        let response: Value = serde_json::from_str(&line.unwrap()).unwrap();
+        if response["id"] == "deferred" {
+            std::fs::write(format!("/state/{plugin}/call-result"), response.to_string()).unwrap();
+            break;
+        }
+    }
+}
+/// Answers a method that version two removes from its interface.
+fn legacy(request: &Value, document: &Value, version: &str) {
+    if document["methods"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .any(|m| m["name"] == "legacy")
+    {
+        send(json!({"jsonrpc":"2.0","id":request["id"],"result":version}));
+    } else {
+        send(
+            json!({"jsonrpc":"2.0","id":request["id"],"error":{"code":-32601,"message":"legacy removed","data":{"version":version}}}),
+        );
+    }
+}
 /// Reads a version-specific discovery document without the SDK.
 fn main() {
     let version = env!("FIXTURE_VERSION");
@@ -16,6 +48,14 @@ fn main() {
         serde_json::from_slice(&std::fs::read(format!("/state/{plugin}/{version}.json")).unwrap())
             .unwrap();
     let result = match request["method"].as_str().unwrap() {
+        "deferred" => {
+            deferred(&request, &plugin, &mut lines);
+            return;
+        }
+        "legacy" => {
+            legacy(&request, &document, version);
+            return;
+        }
         "rpc.discover" => {
             if document["x-test-wait"] == true {
                 std::fs::write(format!("/state/{plugin}/discover-started"), "ready").unwrap();