Phase 63 — Query Plan Review

Extends the existing EXPLAIN inspector with a conservative, read-only query-plan review panel.

Summarises MySQL tabular EXPLAIN steps and flags large full scans (estimated rows >= 10,000), extra sorting and temporary results.
Explains each finding and provides context-aware next steps without creating indexes or running SELECT statements.
Offers Copy Review to share a plain-text report with SQL and findings.
Supports both System, Light and Dark appearances through adaptive SwiftUI colours.
JSON EXPLAIN remains supported; switch to Table to use the per-step diagnostic rules.
Existing SQL autosuggest, persistent introspection, schema-change review and graph dashboards are preserved.

The review uses optimizer estimates, not measured execution timings. An unflagged plan is not proof of good performance.

Validation: static source checks and ZIP integrity only. Requires macOS Xcode build and live MySQL verification.