Move generated project state under ~/.flok

[pamelia]

Summary

• move generated plan, memory, compaction, team, snapshot, and worktree artifacts out of project-local .flok directories
• store per-project runtime state under ~/.flok/projects/-
• keep project-local .flok reserved for user-authored config and skills

Testing

• cargo fmt --all --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace