feat: add Mushaf pages lookup table - #21

Summary

• add a 604-row pages lookup table to the SQLite and PostgreSQL exports
• derive each page's first and last ayah IDs from the source dump's existing ayahs.page values
• validate a complete 6,236-ayah import has a contiguous 1–604 map, while retaining partial mappings for converter fixtures
• document the mapping's source provenance and regenerate schema references

Verification

• just check (36 tests)
• direct source-dump check: 604 pages; page 1 covers ayahs 1–7 and page 604 covers ayahs 6222–6236

The page map is distribution metadata derived from this repository's versioned dump; it does not claim an independent verification of a printed Mushaf layout.