add auth system: users, login, JWT, protected routes

Domain: User entity, AuthPort/PasswordHashPort/SecretStore ports.
Adapters: auth (argon2 hashing, JWT tokens), secret-store (env-based),
config-sqlite user repository, http-api auth routes + extractors.
Application: auth_service. SPA: login page, auth client, protected router.

crates/adapters/auth/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "kframe-auth"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+domain.workspace = true
+jsonwebtoken = "9"
+argon2 = { version = "0.5", features = ["std"] }
+rand_core = { version = "0.6", features = ["getrandom"] }
+serde = { version = "1", features = ["derive"] }