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/runtime.rs

@@ -221,10 +221,21 @@ impl Runtime {
     pub fn new(cache: &Path) -> Result<Arc<Self>> {
         let mut config = Config::new();
         config.epoch_interruption(true);
-        std::fs::create_dir_all(cache)?;
-        let mut cache_config = wasmtime::CacheConfig::new();
-        cache_config.with_directory(cache.canonicalize()?);
-        config.cache(Some(wasmtime::Cache::new(cache_config)?));
+        let disk_cache = (|| -> Result<_> {
+            std::fs::create_dir_all(cache)?;
+            let mut cache_config = wasmtime::CacheConfig::new();
+            cache_config.with_directory(cache.canonicalize()?);
+            Ok(wasmtime::Cache::new(cache_config)?)
+        })();
+        match disk_cache {
+            Ok(cache) => {
+                config.cache(Some(cache));
+            }
+            Err(error) => eprintln!(
+                "compile cache {} unavailable: {error}; running without disk cache",
+                cache.display()
+            ),
+        }
         let engine = Engine::new(&config)?;
 
         let mut linker: Linker<ProcessState> = Linker::new(&engine);