fix: add validation error handling to InactiveJailDetail

- Add validationError state to show network/API failures to user
- Use handleFetchError to properly handle auth errors (suppress generic error banner, trigger session-expiry flow)
- Clear validationError when user clicks Validate again
- Ensure error MessageBar renders instead of success banner when validation fails
- Fix InactiveJailDetail onValidate to return Promise as expected by prop type
- Fix useJailConfigs test to use correct JailConfig interface

Fixes TASK-BUG-05: prevents silent validation failures where user cannot distinguish between clean 'no issues' result and server error.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/src/hooks/__tests__/useJailConfigs.test.ts

@@ -15,27 +15,19 @@ describe("useJailConfigs", () => {
       jails: [
         {
           name: "sshd",
-          enabled: true,
-          active: true,
+          ban_time: 600,
+          find_time: 600,
+          max_retry: 5,
+          fail_regex: [],
+          ignore_regex: [],
+          log_paths: [],
+          date_pattern: null,
+          log_encoding: "auto",
           backend: "systemd",
-          filename: "/etc/fail2ban/jail.d/sshd.conf",
-          source_file: "/etc/fail2ban/jail.d/sshd.conf",
-          last_activation: "2024-01-01T00:00:00Z",
-          bantime: 600,
-          findtime: 600,
-          maxretry: 5,
-          action: [],
-          logpath: [],
-          port: [],
-          ignoreself: false,
-          filter: "sshd",
-          destemail: "",
-          sendername: "",
-          action_d_files: [],
-          ignoreip: [],
-          ignorecommand: "",
-          banaction: "",
-          banaction_allports: false,
+          use_dns: "warn",
+          prefregex: "",
+          actions: [],
+          bantime_escalation: null,
         },
       ],
       total: 1,