fix(cli): surface resolved path in dump-manifests error — ROADMAP #45 partial

Before:
  error: failed to extract manifests: No such file or directory (os error 2)

After:
  error: failed to extract manifests: No such file or directory (os error 2)
    looked in: /Users/yeongyu/clawd/claw-code/rust

The workspace_dir is computed from CARGO_MANIFEST_DIR at compile time and
only resolves correctly when running from the build tree. Surfacing the
resolved path lets users understand immediately why it fails outside the
build context.

ROADMAP #45 root cause (build-tree-only path) remains open.

rust/crates/rusty-claude-cli/src/main.rs

@@ -1933,6 +1933,13 @@ fn looks_like_slash_command_token(token: &str) -> bool {
 
 fn dump_manifests(output_format: CliOutputFormat) -> Result<(), Box<dyn std::error::Error>> {
     let workspace_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("../..");
+    // Surface the resolved path in the error so users can diagnose missing
+    // manifest files without guessing what path the binary expected.
+    // ROADMAP #45: this path is only correct when running from the build tree;
+    // a proper fix would ship manifests alongside the binary.
+    let resolved = workspace_dir
+        .canonicalize()
+        .unwrap_or_else(|_| workspace_dir.clone());
     let paths = UpstreamPaths::from_workspace_dir(&workspace_dir);
     match extract_manifest(&paths) {
         Ok(manifest) => {
@@ -1954,7 +1961,11 @@ fn dump_manifests(output_format: CliOutputFormat) -> Result<(), Box<dyn std::err
             }
             Ok(())
         }
-        Err(error) => Err(format!("failed to extract manifests: {error}").into()),
+        Err(error) => Err(format!(
+            "failed to extract manifests: {error}\n  looked in: {}",
+            resolved.display()
+        )
+        .into()),
     }
 }