Migrate DB from SQLite to Postgres (Prisma + Kysely)

[Blankeos]

Motivation

• Move the app from a local SQLite/libsql setup to Postgres so the project can run against a standard Postgres DB and use native jsonb/timestamp types.
• Use Kysely's PostgresDialect (via pg Pool) for the server-side query client instead of the libsql / bun-worker SQLite dialects.
• Ensure Prisma schema, migrations, runtime types and DAO/service code handle JSON and date fields natively instead of storing them as strings.

Description

• Replaced Kysely dialect with PostgresDialect and a pg Pool in src/server/db/kysely.ts to connect via DATABASE_URL.
• Updated prisma/schema.prisma datasource to provider = "postgresql" and added url = env("DATABASE_URL"), and changed prisma/migrations/* SQL to use JSONB and TIMESTAMP(3) instead of DATETIME.
• Adjusted generated Kysely types in src/server/db/types.ts to introduce Timestamp and use Date/boolean types for expires_at, created_at, updated_at, joined_at, and email_verified.
• Converted DAO/service code to use native Date objects and a jsonEncode/jsonDecode pattern for JSON fields (added/updated usages in src/server/modules/auth/* and src/server/modules/organization/*) so JSON is persisted as jsonb and timestamps as native timestamps.
• Added docker-compose.yml with a postgres:16 service and updated .env.example and README.md to document the example DATABASE_URL (postgresql://solid:solid@localhost:5432/solid_launch?schema=public) and local Postgres startup instructions.
• Updated package manifests/lock to remove the libsql/bun-worker entries and add pg as the runtime dependency (package.json and bun.lock edits).

Testing

• Attempted dependency install with bun install but it failed due to a registry error while resolving pg (GET https://registry.npmjs.org/pg - 403), so full install/build verification could not be completed.
• No automated migrations or runtime integration tests were executed because dependencies could not be installed.

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Codex Task