feat: Bulk Record Upsert / Sync Action Pack #101

Description:

Create a Flow Designer action that can upsert (insert or update) multiple records in a target table using a JSON array input.

Why it matters:

Avoids developers having to build loops or script steps for bulk data syncs.

Inputs:

Target table name
Array of record objects
Matching key(s)

Outputs:

Counts of inserts / updates
Error log

Acceptance Criteria:

Works without exceeding flow limits
Partial failure handling
Input validation