Pi 0.30.1

Fixed

• Sessions saved to wrong directory: In v0.30.0, sessions were being saved to ~/.pi/agent/ instead of ~/.pi/agent/sessions/<encoded-cwd>/, breaking --resume and /resume. Misplaced sessions are automatically migrated on startup. (#320 by @aliou)
• Custom system prompts missing context: When using a custom system prompt string, project context files (AGENTS.md), skills, date/time, and working directory were not appended. (#321)