feat: add FastAPI backend with PostgreSQL and start script fixes

- Add server/ directory with FastAPI backend
- Fix server/start.sh to properly handle venv on Windows/Git Bash
- Add alembic migrations and pyproject.toml
- Add server tests

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

server/src/app/core/__init__.py

@@ -0,0 +1 @@
+__all__ = ["config"]

server/src/app/core/bootstrap.py

@@ -0,0 +1,84 @@
+from __future__ import annotations
+
+from pathlib import Path
+from urllib.parse import quote_plus
+
+from dotenv import set_key
+
+from app.core.config import ROOT_DIR, Settings, refresh_settings
+from app.db.session import configure_session_factory
+from app.schemas.bootstrap import BootstrapSetupPayload, BootstrapStateRead
+
+ENV_FILE = ROOT_DIR / ".env"
+ENV_EXAMPLE_FILE = ROOT_DIR / ".env.example"
+
+
+def ensure_env_file() -> Path:
+    if ENV_FILE.exists():
+        return ENV_FILE
+
+    if ENV_EXAMPLE_FILE.exists():
+        ENV_FILE.write_text(ENV_EXAMPLE_FILE.read_text(encoding="utf-8"), encoding="utf-8")
+    else:
+        ENV_FILE.write_text("", encoding="utf-8")
+
+    return ENV_FILE
+
+
+def build_database_url(payload: BootstrapSetupPayload) -> str:
+    username = quote_plus(payload.postgres_user)
+    password = quote_plus(payload.postgres_password)
+    return (
+        f"postgresql+psycopg://{username}:{password}"
+        f"@{payload.postgres_host}:{payload.postgres_port}/{payload.postgres_db}"
+    )
+
+
+def build_bootstrap_state(settings: Settings) -> BootstrapStateRead:
+    return BootstrapStateRead(
+        initialized=settings.setup_completed,
+        company={
+            "name": settings.company_name,
+            "code": settings.company_code,
+            "admin_email": settings.admin_email,
+        },
+        web={"host": settings.web_host, "port": settings.web_port},
+        server={"host": settings.app_host, "port": settings.app_port},
+        database={
+            "driver": "postgresql",
+            "host": settings.postgres_host,
+            "port": settings.postgres_port,
+            "name": settings.postgres_db,
+            "username": settings.postgres_user,
+            "password_configured": bool(settings.postgres_password),
+        },
+        redis={"enabled": bool(settings.redis_url), "url": settings.redis_url or ""},
+    )
+
+
+def persist_bootstrap_config(payload: BootstrapSetupPayload, settings: Settings) -> BootstrapStateRead:
+    env_file = ensure_env_file()
+    database_url = build_database_url(payload)
+    vite_api_base_url = f"http://{settings.app_host}:{settings.app_port}{settings.api_v1_prefix}"
+
+    updates = {
+        "SETUP_COMPLETED": "true",
+        "COMPANY_NAME": payload.company_name,
+        "COMPANY_CODE": payload.company_code,
+        "ADMIN_EMAIL": payload.admin_email or "",
+        "POSTGRES_HOST": payload.postgres_host,
+        "POSTGRES_PORT": str(payload.postgres_port),
+        "POSTGRES_DB": payload.postgres_db,
+        "POSTGRES_USER": payload.postgres_user,
+        "POSTGRES_PASSWORD": payload.postgres_password,
+        "DATABASE_URL": database_url,
+        "REDIS_URL": payload.redis_url or "",
+        "VITE_API_BASE_URL": vite_api_base_url,
+    }
+
+    for key, value in updates.items():
+        set_key(str(env_file), key, value, quote_mode="auto", encoding="utf-8")
+
+    refreshed_settings = refresh_settings(updates)
+    configure_session_factory()
+    return build_bootstrap_state(refreshed_settings)

server/src/app/core/config.py

@@ -0,0 +1,70 @@
+from __future__ import annotations
+
+from functools import lru_cache
+from os import environ
+from pathlib import Path
+
+from pydantic import Field
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+SERVER_DIR = Path(__file__).resolve().parents[3]
+ROOT_DIR = SERVER_DIR.parent
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(
+        env_file=(ROOT_DIR / ".env", SERVER_DIR / ".env"),
+        env_file_encoding="utf-8",
+        extra="ignore",
+    )
+
+    app_name: str = Field(default="X-Financial Server", alias="APP_NAME")
+    app_env: str = Field(default="local", alias="APP_ENV")
+    app_debug: bool = Field(default=True, alias="APP_DEBUG")
+    setup_completed: bool = Field(default=False, alias="SETUP_COMPLETED")
+
+    company_name: str = Field(default="", alias="COMPANY_NAME")
+    company_code: str = Field(default="", alias="COMPANY_CODE")
+    admin_email: str = Field(default="", alias="ADMIN_EMAIL")
+
+    web_host: str = Field(default="127.0.0.1", alias="WEB_HOST")
+    web_port: int = Field(default=5173, alias="WEB_PORT")
+    app_host: str = Field(default="127.0.0.1", alias="SERVER_HOST")
+    app_port: int = Field(default=8000, alias="SERVER_PORT")
+    api_v1_prefix: str = Field(default="/api/v1", alias="API_V1_PREFIX")
+
+    postgres_host: str = Field(default="127.0.0.1", alias="POSTGRES_HOST")
+    postgres_port: int = Field(default=5432, alias="POSTGRES_PORT")
+    postgres_db: str = Field(default="x_financial", alias="POSTGRES_DB")
+    postgres_user: str = Field(default="postgres", alias="POSTGRES_USER")
+    postgres_password: str = Field(default="postgres", alias="POSTGRES_PASSWORD")
+
+    database_url: str | None = Field(default=None, alias="DATABASE_URL")
+    sqlalchemy_echo: bool = Field(default=False, alias="SQLALCHEMY_ECHO")
+
+    redis_url: str | None = Field(default=None, alias="REDIS_URL")
+    cors_origins: list[str] = Field(default_factory=list, alias="CORS_ORIGINS")
+    vite_api_base_url: str = Field(default="http://127.0.0.1:8000/api/v1", alias="VITE_API_BASE_URL")
+
+    @property
+    def resolved_database_url(self) -> str:
+        if self.database_url:
+            return self.database_url
+
+        return (
+            f"postgresql+psycopg://{self.postgres_user}:{self.postgres_password}"
+            f"@{self.postgres_host}:{self.postgres_port}/{self.postgres_db}"
+        )
+
+
+@lru_cache
+def get_settings() -> Settings:
+    return Settings()
+
+
+def refresh_settings(updated_values: dict[str, str]) -> Settings:
+    for key, value in updated_values.items():
+        environ[key] = value
+
+    get_settings.cache_clear()
+    return get_settings()