feat: add verified Docker database environment

[korex-f]

Summary

• add MySQL 8.4, PostgreSQL 16, and SQLite Docker targets built from the tracked MySQL dump
• make MySQL and PostgreSQL readiness data-aware: healthy only after all 835,624 ayah_edition rows are present
• provide persistent server volumes, host port/password overrides, host-writable SQLite output, and just docker-* commands
• document the source-MySQL versus enriched SQLite/PostgreSQL rub_id models and mark Docker support complete

Verification

• git diff --check
• just docker-check
• just check (33 tests passing)
• clean isolated Compose build/import: MySQL, PostgreSQL, and SQLite each verified at 114 surahs, 6,236 ayahs, 134 editions, and 835,624 ayah_edition rows
• verified Arabic UTF-8 text in every target; SQLite integrity_check returned ok and foreign_key_check was empty
• confirmed MySQL/PostgreSQL health checks and persistent-volume restart behavior
• removed the isolated test containers, network, volumes, and generated SQLite output afterward