Agent jobs (spawn_agents_on_csv) + progress UI (#10935)

## Summary
- Add agent job support: spawn a batch of sub-agents from CSV, auto-run,
auto-export, and store results in SQLite.
- Simplify workflow: remove run/resume/get-status/export tools; spawn is
deterministic and completes in one call.
- Improve exec UX: stable, single-line progress bar with ETA; suppress
sub-agent chatter in exec.

## Why
Enables map-reduce style workflows over arbitrarily large repos using
the existing Codex orchestrator. This addresses review feedback about
overly complex job controls and non-deterministic monitoring.

## Demo (progress bar)
```
./codex-rs/target/debug/codex exec \
  --enable collab \
  --enable sqlite \
  --full-auto \
  --progress-cursor \
  -c agents.max_threads=16 \
  -C /Users/daveaitel/code/codex \
  - <<'PROMPT'
Create /tmp/agent_job_progress_demo.csv with columns: path,area and 30 rows:
path = item-01..item-30, area = test.

Then call spawn_agents_on_csv with:
- csv_path: /tmp/agent_job_progress_demo.csv
- instruction: "Run `python - <<'PY'` to sleep a random 0.3–1.2s, then output JSON with keys: path, score (int). Set score = 1."
- output_csv_path: /tmp/agent_job_progress_demo_out.csv
PROMPT
```

## Review feedback addressed
- Auto-start jobs on spawn; removed run/resume/status/export tools.
- Auto-export on success.
- More descriptive tool spec + clearer prompts.
- Avoid deadlocks on spawn failure; pending/running handled safely.
- Progress bar no longer scrolls; stable single-line redraw.

## Tests
- `cd codex-rs && cargo test -p codex-exec`
- `cd codex-rs && cargo build -p codex-cli`

codex-rs/app-server/tests/suite/v2/experimental_feature_list.rs

@@ -9,6 +9,7 @@ use codex_app_server_protocol::ExperimentalFeatureListResponse;
 use codex_app_server_protocol::ExperimentalFeatureStage;
 use codex_app_server_protocol::JSONRPCResponse;
 use codex_app_server_protocol::RequestId;
+use codex_core::config::ConfigBuilder;
 use codex_core::features::FEATURES;
 use codex_core::features::Stage;
 use pretty_assertions::assert_eq;
@@ -20,6 +21,11 @@ const DEFAULT_TIMEOUT: Duration = Duration::from_secs(10);
 #[tokio::test]
 async fn experimental_feature_list_returns_feature_metadata_with_stage() -> Result<()> {
     let codex_home = TempDir::new()?;
+    let config = ConfigBuilder::default()
+        .codex_home(codex_home.path().to_path_buf())
+        .fallback_cwd(Some(codex_home.path().to_path_buf()))
+        .build()
+        .await?;
     let mut mcp = McpProcess::new(codex_home.path()).await?;
 
     timeout(DEFAULT_TIMEOUT, mcp.initialize()).await??;
@@ -63,7 +69,7 @@ async fn experimental_feature_list_returns_feature_metadata_with_stage() -> Resu
                 display_name,
                 description,
                 announcement,
-                enabled: spec.default_enabled,
+                enabled: config.features.enabled(spec.id),
                 default_enabled: spec.default_enabled,
             }
         })