Refine project vision document

[jmcte]

Summary

• Refine VISION.md for mailplus-intelligence after reviewing the current README, repo docs, manifest, and product surfaces.
• Replace generic first-pass language with repo-specific product boundaries, principles, near-term direction, and non-goals.

Governing Issue

• No issue is linked because this PR was created directly from the operator request to take another pass after reviewing each repository.
• This is documentation-only planning work and does not close a tracked implementation issue.

Validation

• Not run; documentation-only change.
• Verified each refinement branch changes only VISION.md.
• Verified updated VISION.md files are ASCII-only.

Bootstrap Governance

• No bootstrap-managed files changed.
• No GitHub policy, runner, release, or repository settings changed.

Merge Automation

• Not enabled. Please review and merge manually after the refined draft matches the product direction.

Notes

• Follow-up to the first-pass VISION.md seed PRs that have already merged.

[pheidon]

Docs-only refinement looks sound: single-file update, no bootstrap/governance changes, and the scope matches the repo-specific planning pass.

[pheidon]

Docs-only refinement looks sound: single-file vision doc update, no bootstrap or governance changes, and the scope matches the repo-specific planning pass.