fix: improve imap robustness and update dependencies

[WeekendSuperhero]

Summary

• Fixed serious IMAP issues to improve robustness.
• Upgraded rmcp to v2.2.0 and added idna and psl crates.
• Added nightly stress testing for large mailboxes.
• Added weekly security auditing workflow.
• Pinned reusable GitHub workflows and locked CI dependencies.

Changes

IMAP

• Updated COMPRESS=DEFLATE negotiation to occur only if advertised by the server.
• Bumped agentmail version to 0.4.0.

Dependencies

• Upgraded rmcp to v2.2.0.
• Added idna and psl crates.

CI/CD

• Pinned GitHub reusable workflows to a specific commit hash.
• Added nightly-stress.yml for testing large mailbox parsing.
• Added security.yml for automated auditing with cargo-audit.
• Added --locked flag to cargo commands in CI and release workflows.

Test plan

• Verify IMAP connection and sync with various providers.
• Run nightly stress test manually to verify large mailbox parsing.
• Check GitHub Actions to ensure CI passes.
• Verify core app functionality with new dependencies.

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PR description generated by Agent

[github-actions]

🤖 Muse — Security · ✅ pass

Round 3 · reviewed 73c885b · 0 open · 0 resolved this round

Summary: The changes since the last review consist solely of a minor version bump in Cargo.toml. No new security issues, dependency risks, or trust boundary violations were identified.

_{Re-run: add the muse:review label · force same-SHA re-run: muse:force}

[github-actions]

🤖 Muse — Test Coverage · ✅ pass

Round 3 · reviewed 73c885b · 0 open · 0 resolved this round

Summary: The changes in this diff consist entirely of updates to GitHub Actions workflows, workflow pinning, and dependency/version bumps in Cargo.toml. Since there are no behavioral changes to the application code, no new test coverage is required.

_{Re-run: add the muse:review label · force same-SHA re-run: muse:force}

[github-actions]

🤖 Muse — Code Review · ✅ pass

Round 3 · reviewed 73c885b · 0 open · 0 resolved this round

Summary: The only change since the last review is a version bump to 0.5.0 in Cargo.toml. No new issues or defects were identified.

_{Re-run: add the muse:review label · force same-SHA re-run: muse:force}