chore: add SPDX license headers to documentation files

[karagozemin]

Add an SPDX license header to the documentation files so license provenance is visible per-file (the repo is MIT-licensed).

Mechanical change — prepend this exact line as the first line of each file, nothing else:

<!-- SPDX-License-Identifier: MIT -->

Add it to the following files:

• ARCHITECTURE.md
• README.md
• TASKS.md
• contracts/round/ERRORS.md
• contracts/round/README.md
• docs/CV_LABS_APPLICATION.md
• docs/DEMO_SCRIPT.md
• docs/DEPLOY.md
• docs/ECOSYSTEM.md
• docs/INTEGRATION.md
• docs/LIMITATIONS.md
• docs/PILOT_PLAYBOOK.md
• docs/RECEIPTS.md
• docs/SCF_PLAN.md
• docs/SCF_TRANCHE_PLAN.md
• docs/TECH_DESIGN.md
• docs/THREAT_MODEL.md
• docs/TRACK_ANSWERS.md
• examples/grant-scoring/README.md
• packages/round-bindings/README.md
• packages/round-bindings/SNAPSHOT_TESTS.md
• services/appraisal-api/README.md
• services/keeper/README.md

[Peculiarr7]

Hi! I’m a full-stack developer with a strong blockchain background, and I’m confident I can resolve this issue quickly and effectively. I’ll deliver a clean, reliable solution with immediate attention to detail, ensuring it’s completed as soon as possible. Please assign it to me—I’m ready to get started right away.

[Caneryy]

Can I work on this issue?

[grantfox-oss]

🦊 GrantFox — @Caneryy has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #216)
2. Your PR will be reviewed by the Sub-Rosa-Issue maintainers

Good luck! Track your progress on GrantFox.