Add Sigli.ai DAWE Proposal

This proposal seeks funding to build and open-source the DAML Automated Workflow Evaluator (DAWE), a scenario-based automated security and QA testing framework for DAML applications on Canton.

Checklist

• [x] Proposal file added under /proposals/
• [x] Milestones and funding amounts defined
• [x] Acceptance criteria included
• [x] Alignment with Canton priorities described

SIG: daml-tooling