feat(codex): create initial workspace index and journal for AI development sessions

.trellis/workspace/codex/index.md

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+# Workspace Index - codex
+
+> Journal tracking for AI development sessions.
+
+---
+
+## Current Status
+
+<!-- @@@auto:current-status -->
+- **Active File**: `journal-1.md`
+- **Total Sessions**: 0
+- **Last Active**: -
+<!-- @@@/auto:current-status -->
+
+---
+
+## Active Documents
+
+<!-- @@@auto:active-documents -->
+| File | Lines | Status |
+|------|-------|--------|
+| `journal-1.md` | ~0 | Active |
+<!-- @@@/auto:active-documents -->
+
+---
+
+## Session History
+
+<!-- @@@auto:session-history -->
+| # | Date | Title | Commits | Branch |
+|---|------|-------|---------|--------|
+<!-- @@@/auto:session-history -->
+
+---
+
+## Notes
+
+- Sessions are appended to journal files
+- New journal file created when current exceeds 2000 lines
+- Use `add_session.py` to record sessions

.trellis/workspace/codex/journal-1.md

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+# Journal - codex (Part 1)
+
+> AI development session journal
+> Started: 2026-09-01
+
+---
+