Feature: migration diff/status tool for local files vs remote history

[sujaritnrc]

Problem

It is hard to quickly detect:

• missing local versions
• extra local versions
• duplicate version prefixes
• out-of-order naming mismatches

without manual scripting.

Proposed Solution

Add MCP tool migration_status_diff that compares:

• local migration directory metadata
• remote schema_migrations history

Desired Output

Structured JSON with:

• missing_local: []
• extra_local: []
• duplicate_local_versions: []
• name_mismatches: []
• ready_to_push: boolean
• suggested_actions: []

Why this matters

This would prevent common migration failures early and make plugin-first workflows much more reliable.