feat: add a version RPC returning the daemon build version

RPC clients (the hephaestus.nvim plugin, for its `:Heph version`
command) had no way to learn which hephd they are talking to — `health`
returns counts, not a version. Add a tiny `version` method returning
`{ version: heph_core::VERSION }`, the same `X.Y.Z (sha)` string the
binaries print for --version. No store access needed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/hephd/src/rpc.rs

@@ -417,6 +417,7 @@ pub fn dispatch(store: &mut dyn Store, method: &str, params: Value) -> Result<Va
             let p: ViewParams = parse(params)?;
             json!(store.resolve_project(&p.name)?)
         }
+        "version" => json!({ "version": heph_core::VERSION }),
         "health" => json!(store.health()?),
         "search" => {
             let p: SearchParams = parse(params)?;

crates/hephd/tests/rpc_socket.rs

@@ -109,6 +109,37 @@ fn node_resolve_is_exact_not_fuzzy_over_socket() {
     assert_eq!(missing, Value::Null);
 }
 
+#[test]
+fn version_rpc_returns_build_version() {
+    let (socket, _dir) = spawn_daemon();
+    let mut c = client(&socket);
+
+    let got = c.call("version", json!({})).unwrap();
+    assert_eq!(got["version"], heph_core::VERSION);
+}
+
+#[test]
+fn project_resolve_is_case_insensitive_and_prefix_fuzzy_over_socket() {
+    let (socket, _dir) = spawn_daemon();
+    let mut c = client(&socket);
+
+    let proj = c
+        .call("node.create", json!({ "kind": "project", "title": "Hephaestus" }))
+        .unwrap();
+    let pid = proj["id"].as_str().unwrap().to_string();
+
+    // Case-insensitive exact and unambiguous prefix both resolve to the project.
+    for name in ["Hephaestus", "hephaestus", "heph"] {
+        let got = c.call("project.resolve", json!({ "name": name })).unwrap();
+        assert_eq!(got["id"], pid, "resolving {name:?}");
+    }
+    // An unknown name is JSON null, not an error.
+    let missing = c
+        .call("project.resolve", json!({ "name": "nope" }))
+        .unwrap();
+    assert_eq!(missing, Value::Null);
+}
+
 #[test]
 fn task_create_appears_in_next_with_context_link() {
     let (socket, _dir) = spawn_daemon();

docs/changelog.d/version-rpc.feature.md

@@ -0,0 +1 @@
+New `version` RPC returns the daemon's build version (`heph_core::VERSION`, e.g. `1.0.0 (ab6701d12)`), so RPC clients — notably the `hephaestus.nvim` plugin's `:Heph version` command — can report which `hephd` they are talking to without shelling out to the binary.