[PLAT-440] roll up routing in metrics view

[pjain1]

• Add rollup table config to metrics view proto and YAML parser
• Implement query routing: eligible rollups are selected based on grain derivability, dimension/measure coverage, timezone match, time range alignment, and time coverage
• Prefer coarsest grain among eligible rollups; break ties by smallest data range
• For no-time-range queries ("all data"), verify the rollup covers the base table's full range rather than skipping coverage checks

Checklist:

• Covered by tests
• Ran it and it works as intended
• Reviewed the diff before requesting a review
• Checked for unhandled edge cases
• Linked the issues it closes
• Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• Intend to cherry-pick into the release branch
• I'm proud of this work!