feat(migrate): expand syntax support and harden placeholder parsing

[rmorehig]

Summary

• Expand migrate parser and generator support across datasource and pipe syntax, including sink/import and parameter handling.
• Make placeholder parsing robust when descriptions include text like analyze (defaults to 1 day).
• Normalize parameter inference and default propagation for migration output.
• Add and update migrate/generator tests for duplicate/default and syntax coverage.

Validation

• Ran migrate test suite file: src/cli/commands/migrate.test.ts (all tests passed).
• Ran migration command from example directory: npx tinybird migrate data_project --force (completed without errors).