Feat: Implement basic web authentication and UI

This commit introduces the foundation for web-based authentication and
user interface. It includes:

- **Session Management**: Securely handling user sessions using
  cryptographically generated tokens, cookies with appropriate security
  flags, and server-side storage.
- **Login/Logout Functionality**: Endpoints for users to log in with
  their credentials and log out, clearing their session.
- **User Interface**: Basic templates for the login page, a list of
  cases, and a detailed view of a single case, allowing users to
  navigate and view their data.
- **Authorization**: An `AuthenticatedWebUser` extractor to ensure only
  logged-in users can access protected web routes.
- **Configuration**: Added a `cookie_secure` option to the configuration
  to control the `Secure` flag on session cookies, useful for local
  development.
- **Dependencies**: Added necessary dependencies for password hashing,
  time handling, and TOML file manipulation.
- **Helper Binary**: Included a `hash-password` binary to simplify
  generating bcrypt hashes for user passwords.

server/src/web_session.rs

@@ -0,0 +1,17 @@
+use std::collections::HashMap;
+use std::sync::Arc;
+use std::time::Instant;
+
+use tokio::sync::RwLock;
+
+pub struct WebSession {
+    pub slug: String,
+    pub role: String,
+    pub expires_at: Instant,
+}
+
+pub type SessionStore = Arc<RwLock<HashMap<String, WebSession>>>;
+
+pub fn new_store() -> SessionStore {
+    Arc::new(RwLock::new(HashMap::new()))
+}