chore: add copyright headers to tlock and drand tools

[emirykl]

Summary

• add the MIT copyright notice as the first line of the 17 requested source files
• cover tlock, round-bindings, drand-tools, and appraisal-api
• make no behavioral or unrelated changes

Test evidence

• 100 package tests passed across the four affected packages
• TypeScript typechecks passed for all four affected packages
• exact first-line header audit passed for all 17 files
• git diff --check passed

Fixes #203

Verification

• tlock tests: 41 passed
• round-bindings tests: 17 passed
• drand-tools tests: 5 passed
• appraisal-api tests: 37 passed
• TypeScript typechecks passed for all four affected packages
• Exact first-line header audit passed for all 17 files
• git diff --check passed

Diagnostics

Recovered command failures: /bin/zsh -lc 'pnpm --filter @sub-rosa/round-bindings typecheck' (127), /bin/zsh -lc 'pnpm --filter @sub-rosa/tlock test' (127), /bin/zsh -lc 'pnpm --filter @sub-rosa/round-bindings test' (127), /bin/zsh -lc 'pnpm --filter @sub-rosa/drand-tools test' (127), /bin/zsh -lc 'pnpm --filter @sub-rosa/drand-tools typecheck' (127), /bin/zsh -lc 'pnpm --filter @sub-rosa/tlock typecheck' (127), /bin/zsh -lc 'pnpm --filter @sub-rosa/appraisal-api typecheck' (127), /bin/zsh -lc 'pnpm --filter @sub-rosa/appraisal-api test' (127)