Align plugin descriptions with app submissions

[ashwinm-oai]

Summary

• Align 38 plugin manifest descriptions with submitted app-admin values
• Keep top-level description in sync with interface.shortDescription
• Leave connector-only/non-local rows untouched

Verification

• Re-read Bulk Connector to Plugin Conversion sheet
• Verified 39 Apps SDK rows through app-admin-read using versions/list/{app_id} and exact version hydration
• Verified Intercom connector rows via plugins/intercom/.app.json
• Ramp and Metabase have no local plugin directory/.app.json in this checkout
• Ran JSON manifest validation for changed files
• Ran git diff --check