fix: ensure /tmp/gh-aw exists before activation job scripts run

[Copilot]

The Metrics Collector activation job was crashing with ENOENT: no such file or directory, open '/tmp/gh-aw/aw_info.json' because setup.sh never created /tmp/gh-aw/ — only /opt/gh-aw/* paths were guaranteed. The generate_aw_info.cjs module has a mkdirSync guard, but that's a secondary safeguard; the directory should exist before any script touches it.

Changes

• actions/setup/setup.sh: Add mkdir -p /tmp/gh-aw immediately after the main destination directory is created, so the path is guaranteed for all jobs using ./actions/setup — including the activation job where create_gh_aw_tmp_dir.sh is never called (it runs only in the agent job).

Original prompt

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This section details on the original issue you should resolve

<issue_title>[workflow-health] Metrics Collector failing — ENOENT: /tmp/gh-aw/aw_info.json</issue_title>
<issue_description>The Metrics Collector workflow has begun failing in the activation job with an unexpected infrastructure error. This is a regression from its previously stable state (5+ consecutive successes as of 2026-02-25).

Error Details

Workflow: Metrics Collector - Infrastructure Agent
Run: §22526204448 (run #73, 2026-02-28T18:13)
Job: activation
Error:

Error: ENOENT: no such file or directory, open '/tmp/gh-aw/aw_info.json'
    at Object.writeFileSync (node:fs:2415:20)
    at eval (eval at callAsyncFunction ...
```

### Root Cause Analysis

The `activation` job fails when `generateWorkflowOverview(core)` tries to write `/tmp/gh-aw/aw_info.json`. This file is created by the `gh-aw setup` action as part of initialization. The error indicates `/tmp/gh-aw/` directory did not exist when the activation job ran.

Possible causes:
1. **Transient runner failure**: The setup step may have failed silently and the directory was never created
2. **Setup action regression**: A recent change to the setup action may have broken directory creation
3. **Race condition**: The setup step may complete but not have created the expected path

### Impact

- Metrics Collector is our infrastructure agent — it provides daily metrics for other meta-orchestrators (Campaign Manager, Agent Performance Analyzer, Workflow Health Manager)
- Failure of this workflow degrades shared memory quality and trend analysis
- Without fresh metrics, health monitoring relies on stale data

### Suggested Fix

1. Check recent changes to `actions/setup` and the `generate_workflow_overview.cjs` script
2. Verify the setup action properly creates `/tmp/gh-aw/` before the activation job runs
3. Add explicit directory creation guard (`mkdir -p /tmp/gh-aw`) in setup if missing

### Debugging

```
/agent agentic-workflows debug the agentic workflow metrics-collector failure in https://github.com/github/gh-aw/actions/runs/22526204448

Detected by: Workflow Health Manager, run §22538460268

Generated by Workflow Health Manager - Meta-Orchestrator

• expires on Mar 2, 2026, 7:28 AM UTC

Comments on the Issue (you are @copilot in this section)

• Fixes [workflow-health] Metrics Collector failing — ENOENT: /tmp/gh-aw/aw_info.json #19019

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[Copilot]

Pull request overview

Ensures the Metrics Collector activation job doesn’t crash with ENOENT by guaranteeing /tmp/gh-aw exists before any activation scripts attempt to write into it.

Changes:

• Create /tmp/gh-aw during actions/setup/setup.sh initialization.
• Add log output indicating the temp directory was created.

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[Copilot]

This script already uses create_dir for directory creation (likely centralizing error handling, permissions, logging, and consistent behavior). For consistency and to avoid bypassing any safeguards in create_dir, consider using create_dir \"/tmp/gh-aw\" here (and quoting the path) instead of calling mkdir -p directly.

Suggested change

	mkdir -p /tmp/gh-aw
	create_dir "/tmp/gh-aw"