Add acme scripts for interacting with ollie:
- AskFile: describe the current file
- Explain: explain selected code
- Document: add documentation comments
- Fix: fix selected code
- Refactor: refactor selected code
- AddTests: write unit tests for selection
- SendVerbatim: send selection as-is
Scripts use the acme 9P filesystem to read selections and pipe
prompts to ollie via 'o prompt'.
Also update justfile to install/uninstall the acme scripts.