Proj d01/design postgre sql schemas

[georges-nasrallah]

Summary

Design and document the PostgreSQL schema for all five services, establishing per-service migration files as the single source of truth for database structure.

Closes #17

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Motivation & Context

Before any service implementation can begin, the database schema must be agreed upon and documented. This PR establishes the schema-per-service approach using Flyway (Spring Boot services) and Alembic (Python services), replacing the previous empty central services/db/schema.sql.

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Changes

• Added Flyway migration + README for auth (users, refresh_tokens)
• Added Flyway migration + README for document (profiles, work_experiences, educations, skills, certifications,
  languages, cover_letters, resumes)
• Added Flyway migration + README for application (applications, fit_analyses)
• Added Alembic migration + README for email (email_connections, processed_emails) — moved from Spring Boot to
  Python/FastAPI
• Added Alembic migration + README for genai (chat_sessions with pgvector embedding, chat_messages, user_memory)
• Removed central services/db/schema.sql in favour of per-service migrations
• Updated CLAUDE.md to reflect email service language change and current state
• Fixed docker-compose.yml postgres hostname from postgres to postgres-db in auth datasource URL

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Steps for Testing

1. Review each migration file under services/<name>/src/main/resources/db/migration/ (Spring Boot) or
   services/<name>/alembic/versions/ (Python)
2. Verify schema matches DB_SCHEMAS.md (gitignored, available locally)
3. No runtime verification needed - migration files require Flyway/Alembic wiring which is a follow-up task per service owner (see each service README)

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Checklist

• I have self-reviewed the diff
• Code is clean — no debug statements, commented-out code, or TODOs left behind
• All CI checks pass (build · test · lint)
• [] Tests added or updated to cover the changes (if needed) — N/A, schema only
• [] New env vars added to .env.example — N/A
• [] OpenAPI spec updated and codegen re-run — N/A
• [] Screenshots or screen recordings attached for any UI changes — N/A

[georges-nasrallah]

The database schemas in this PR are a baseline setup. Each service owner is free to modify their schema if needed as implementation progresses. The SQL migration files are intentionally left unwired connecting Flyway (Spring Boot) or
Alembic (Python) to each service.