core: review fixes, init builds the agent, console without a terminal

Activation path (review T6R): a broken plugin or a stray file in
/plugins blocks no activation; candidates replace their own entries;
discovery has a 10 s deadline and its process is stopped after the
answer; an unchanged hash keeps plugin.prev.wasm; activations run in
their own task; the watcher is not recursive; no duplicate services;
rpc.retired waits for live processes of its version; reads and hashes
on blocking threads.

Guest I/O and per-call paths: a stdin write error is EOF, stdout and
stderr are drained before the status; stderr is lossy UTF-8 and goes
to the journal from its own reader; compiled components are freed;
shutdown starts no new processes; lock queues drop stopping processes;
compile before the admission gate; CommandPre per component;
core.unlock in order; null errors are successes; the journal thread
survives SQLite errors.

sausage init builds the agent with cargo.build; sausage without a
command creates ./world. The console reads plain lines without a
terminal. PROTOCOL.md and DECISIONS.md describe the decided rules. The
flake tests the whole workspace and checks the packaged cargo.build.

cli/Cargo.toml

@@ -31,6 +31,7 @@ sausage-interface = { version = "0.1.0", path = "../interface" }
 notify = "8.2.0"
 rustyline = "19"
 nix = { version = "0.31.3", features = ["signal", "process"] }
+chrono = { version = "0.4.42", default-features = false, features = ["clock"] }
 
 [dev-dependencies]
 hyper = { version = "1.12.0", features = ["server", "http1"] }