fix: parse -o flag correctly to resolve output filename

Fix bug where -o flag value was read as pointer instead of string value,
causing memory addresses to be printed and output path to resolve to ".xlsx".

AGENTS.md

@@ -0,0 +1,73 @@
+# Agent Instructions
+
+## Plans
+
+- Make the plan extremely concise. Sacrifice grammar for the sake of concision.
+- At the end of each plan, give me a list of unresolved questions to answer, if any.
+
+## Issue Tracking
+
+This project uses **br** (beads_rust) for issue tracking and **bv** (beads_viewer) for triage/prioritization. Issues are stored in `.beads/` and tracked in git.
+
+### Tool Roles
+
+| Tool | Role | Key Commands |
+|------|------|--------------|
+| `br` | Issue management (CRUD) | `br ready`, `br show`, `br update`, `br close`, `br sync` |
+| `bv` | Triage & prioritization | `bv --robot-triage` |
+
+### Quick Reference
+
+```bash
+br ready              # Find available work
+br show <id>          # View issue details
+br update <id> --status in_progress  # Claim work
+br close <id>         # Complete work
+br sync               # Sync with git
+```
+
+### What to work on next?
+
+```bash
+bv --robot-triage     # AI-powered recommendation for next issue (preferred)
+br ready              # Fallback: plain list of unblocked issues
+```
+
+> **Warning:** bare `bv` (without flags) launches an interactive TUI that blocks the session. Always use `bv --robot-triage` or other non-interactive flags in automated contexts.
+
+### Key Concepts
+
+- **Dependencies**: Issues can block other issues. `br ready` shows only unblocked work.
+- **Priority**: P0=critical, P1=high, P2=medium, P3=low, P4=backlog (use numbers 0-4, not words)
+- **Types**: task, bug, feature, epic, chore, docs, question
+- **Blocking**: `br dep add <issue> <depends-on>` to add dependencies
+
+
+### Creating issues
+
+You might be tasked with creating a new issue or you discover new tasks by yourself. Use the `/create-single-issue` command accordingly the create a new issue.
+
+## Main Workflow
+
+### Work on issue
+
+You are tasked by the operator to work on an issue.
+It's either a specific issue (`/start-issue <id>`) or the *next* issue (`/start-next-issue`).
+The command tells you to open the issue, enter plan mode and then implement the plan.
+The command tells you explicitly *NOT* to: close the issue, commit or push anything (because this is subject to `/finish-issue`).
+
+### Operator tests manually
+
+After finishing the implementation the operator tests the solution.
+
+### Finish issue
+
+After testing you are tasked by the operator to finish the issue (`/finish-issue`).
+You close the issue and create a commit.
+
+## Release Workflow
+
+Once in a while the operator uses these commands:
+
+- `/tag-version` - you create a new version using the `git tag` mechanism
+- `/update-changelog` - you update the CHANGELOG.md according to the changes of the last version