[FEAT]: Batch LLM extraction for faster PDF processing

[Harshitha-arch]

Description

Currently, FireForm processes each PDF field sequentially with independent LLM calls, which increases latency for multi-field forms.

Rationale

Batched processing can improve performance and scalability by sending all fields in a single structured prompt and mapping JSON output to PDF fields.

Proposed Solution

• Change extraction logic to handle all fields in one request
• Map JSON output to PDF fields
• Update relevant tests and documentation

Acceptance Criteria

• Latency for multi-field PDFs decreases
• JSON output matches schema
• Works in Docker container

Additional Context

This aligns with my GSoC proposal focused on improving FireForm's pipeline efficiency.