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/core/tests/common/test_codex.rs

@@ -215,6 +215,14 @@ impl TestCodexBuilder {
         }
         if let Ok(path) = codex_utils_cargo_bin::cargo_bin("codex") {
             config.codex_linux_sandbox_exe = Some(path);
+        } else if let Ok(exe) = std::env::current_exe()
+            && let Some(path) = exe
+                .parent()
+                .and_then(|parent| parent.parent())
+                .map(|parent| parent.join("codex"))
+            && path.is_file()
+        {
+            config.codex_linux_sandbox_exe = Some(path);
         }
 
         let mut mutators = vec![];