feat: Add Codex CLI compatibility

- Add agents/openai.yaml for Codex skill discovery
- Make SKILL.md script path portable (repo, Claude, Codex, agents dirs)
- Platform-neutral output text ("assistant" instead of "Claude")
- Sandbox-friendly cache/output dirs with env var overrides and tempdir fallback
- Add Codex installation docs to README

Inspired by PR #24 (el-analista) and PR #5 (jblwilliams).
Zero impact on existing Claude Code behavior.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/lib/render.py

@@ -1,6 +1,8 @@
 """Output rendering for last30days skill."""
 
 import json
+import os
+import tempfile
 from pathlib import Path
 from typing import List, Optional
 
@@ -10,8 +12,17 @@ OUTPUT_DIR = Path.home() / ".local" / "share" / "last30days" / "out"
 
 
 def ensure_output_dir():
-    """Ensure output directory exists."""
-    OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
+    """Ensure output directory exists. Supports env override and sandbox fallback."""
+    global OUTPUT_DIR
+    env_dir = os.environ.get("LAST30DAYS_OUTPUT_DIR")
+    if env_dir:
+        OUTPUT_DIR = Path(env_dir)
+
+    try:
+        OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
+    except PermissionError:
+        OUTPUT_DIR = Path(tempfile.gettempdir()) / "last30days" / "out"
+        OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
 
 
 def _assess_data_freshness(report: schema.Report) -> dict:
@@ -35,7 +46,7 @@ def _assess_data_freshness(report: schema.Report) -> dict:
 
 
 def render_compact(report: schema.Report, limit: int = 15, missing_keys: str = "none") -> str:
-    """Render compact output for Claude to synthesize.
+    """Render compact output for the assistant to synthesize.
 
     Args:
         report: Report data
@@ -61,7 +72,7 @@ def render_compact(report: schema.Report, limit: int = 15, missing_keys: str = "
 
     # Web-only mode banner (when no API keys)
     if report.mode == "web-only":
-        lines.append("**🌐 WEB SEARCH MODE** - Claude will search blogs, docs & news")
+        lines.append("**🌐 WEB SEARCH MODE** - assistant will search blogs, docs & news")
         lines.append("")
         lines.append("---")
         lines.append("**⚡ Want better results?** Add API keys to unlock Reddit & X data:")
@@ -204,7 +215,7 @@ def render_compact(report: schema.Report, limit: int = 15, missing_keys: str = "
             lines.append(f"  *{item.why_relevant}*")
             lines.append("")
 
-    # Web items (if any - populated by Claude)
+    # Web items (if any - populated by the assistant)
     if report.web_error:
         lines.append("### Web Results")
         lines.append("")
@@ -356,15 +367,15 @@ def render_full_report(report: schema.Report) -> str:
             lines.append(f"> {item.snippet}")
             lines.append("")
 
-    # Placeholders for Claude synthesis
+    # Placeholders for assistant synthesis
     lines.append("## Best Practices")
     lines.append("")
-    lines.append("*To be synthesized by Claude*")
+    lines.append("*To be synthesized by assistant*")
     lines.append("")
 
     lines.append("## Prompt Pack")
     lines.append("")
-    lines.append("*To be synthesized by Claude*")
+    lines.append("*To be synthesized by assistant*")
     lines.append("")
 
     return "\n".join(lines)