Trim the harness to what it needs to keep going

Host:
- test first: a new version is tested where it lies; only an installed
  version goes to versions/, and instances run from there
- data/ and public/ are shared by all versions; no snapshots; rollback
  restores code only
- no re-delivery, status.json, list, remove/archive, smoke test, data/
  hiding, or stdin timeout; rollback needs a version
- supervisor.rs split out; one place for installing a version
- init only writes the agent folder; run installs it like any actor
- console: @actor, text to the agent, /help, /quit

Agent:
- every text goes out as a broadcast; 5-line prompt; 5 tools that describe
  themselves; turn.json only marks an active turn

Docs: PROTOCOL.md, README.md, DECISIONS.md, AGENTS.md rewritten.
Examples: only notes and notes-v2.

cli/src/world.rs

@@ -8,11 +8,9 @@
 //!     actor.json        version, running, subscriptions (broker)
 //!     source/           source of the current version
 //!     public/           written by the actor, read-only for others
-//!     data/             private state; hidden from other actors
-//!     status.json       runtime state (broker)
+//!     data/             state, writable only by the actor
 //!     stderr.log        stderr of the actor and notes of the broker
-//!     versions/<n>/     actor.wasm, source/, meta.json, snapshot/{data,public}
-//!   archive/            removed actors
+//!     versions/<n>/     every version that was installed: actor.wasm, source/, meta.json
 //! ```
 
 use std::collections::BTreeSet;
@@ -62,9 +60,6 @@ pub struct VersionMeta {
     /// The actor that requested the version ("scan" for a file found on disk).
     pub requested_by: String,
     pub created_at: u64,
-    /// Why the broker did not install this version, if it did not.
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub rejected: Option<String>,
 }
 
 pub fn valid_id(id: &str) -> bool {
@@ -126,8 +121,6 @@ impl World {
         }
         for id in NATIVE {
             world.ensure_actor_dirs(id)?;
-            let status = serde_json::json!({"id": id, "kind": "native", "state": "built-in"});
-            write_atomic(&world.actor_dir(id).join("status.json"), serde_json::to_string_pretty(&status)?.as_bytes())?;
         }
         Ok(world)
     }
@@ -161,6 +154,19 @@ impl World {
         write_atomic(&self.actor_dir(id).join("actor.json"), serde_json::to_string_pretty(meta)?.as_bytes())
     }
 
+    /// Make `actor.wasm` and `source/` a copy of `versions/<version>/`,
+    /// unless `actor.wasm` already is that version (it came from there).
+    pub fn install_files(&self, id: &str, version: u64) -> Result<()> {
+        let dir = self.version_dir(id, version);
+        self.ensure_actor_dirs(id)?;
+        let wasm = std::fs::read(dir.join("actor.wasm"))?;
+        if std::fs::read(self.wasm_path(id)).ok().as_ref() == Some(&wasm) {
+            return Ok(());
+        }
+        write_atomic(&self.wasm_path(id), &wasm)?;
+        replace_tree(&dir.join("source"), &self.source_dir(id))
+    }
+
     /// Version numbers in `versions/`, ascending.
     pub fn versions(&self, id: &str) -> Vec<u64> {
         let mut v: Vec<u64> = std::fs::read_dir(self.versions_dir(id))