feat: initialize rust backend with axum server, seaorm models, and project scaffolding

backend/sample.config.yaml

@@ -0,0 +1,25 @@
+# Sample Configuration for zhealth-backend
+# Copy this to config.yaml and update values as needed.
+# Secrets should be loaded from environment variables using ${VAR_NAME} syntax.
+
+server:
+  host: "127.0.0.1"
+  port: 3000
+
+paths:
+  database: "./data/zhealth.db"
+  logs: "./logs"
+
+logging:
+  level: "info"  # Options: trace | debug | info | warn | error
+
+auth:
+  session_secret: "${SESSION_SECRET}"
+  session_expiry_hours: 24
+  cookie_name: "zhealth_session"
+  cookie_secure: false  # Set to true in production with HTTPS
+
+ai:
+  provider: "gemini"  # Options: gemini | openai | anthropic
+  model: "gemini-3-flash-preview"
+  api_key: "${AI_API_KEY}"