feat(stage-1): inactive jail discovery and activation

- Backend: config_file_service.py parses jail.conf/jail.local/jail.d/*
  following fail2ban merge order; discovers jails not running in fail2ban
- Backend: 3 new API endpoints (GET /jails/inactive, POST /jails/{name}/activate,
  POST /jails/{name}/deactivate); moved /jails/inactive before /jails/{name}
  to fix route-ordering conflict
- Frontend: ActivateJailDialog component with optional parameter overrides
- Frontend: JailsTab extended with inactive jail list and InactiveJailDetail pane
- Frontend: JailsPage JailOverviewSection shows inactive jails with toggle
- Tests: 57 service tests + 16 router tests for all new endpoints (all pass)
- Docs: Features.md, Architekture.md, Tasks.md updated; Tasks 1.1-1.5 marked done

frontend/src/types/config.ts

@@ -380,3 +380,60 @@ export interface JailFileConfig {
 export interface JailFileConfigUpdate {
   jails?: Record<string, JailSectionConfig> | null;
 }
+
+// ---------------------------------------------------------------------------
+// Inactive jail models (Stage 1)
+// ---------------------------------------------------------------------------
+
+/**
+ * A jail discovered in fail2ban config files that is not currently active.
+ *
+ * Maps 1-to-1 with the backend ``InactiveJail`` Pydantic model.
+ */
+export interface InactiveJail {
+  /** Jail name from the config section header. */
+  name: string;
+  /** Filter name (may include mode suffix, e.g. ``sshd[mode=normal]``). */
+  filter: string;
+  /** Action references listed in the config (raw strings). */
+  actions: string[];
+  /** Port(s) to monitor, or null. */
+  port: string | null;
+  /** Log file paths to monitor. */
+  logpath: string[];
+  /** Ban duration as a raw config string (e.g. ``"10m"``), or null. */
+  bantime: string | null;
+  /** Failure-counting window as a raw config string, or null. */
+  findtime: string | null;
+  /** Number of failures before a ban is issued, or null. */
+  maxretry: number | null;
+  /** Absolute path to the config file where this jail is defined. */
+  source_file: string;
+  /** Effective ``enabled`` value — always ``false`` for inactive jails. */
+  enabled: boolean;
+}
+
+export interface InactiveJailListResponse {
+  jails: InactiveJail[];
+  total: number;
+}
+
+/**
+ * Optional override values when activating an inactive jail.
+ */
+export interface ActivateJailRequest {
+  bantime?: string | null;
+  findtime?: string | null;
+  maxretry?: number | null;
+  port?: string | null;
+  logpath?: string[] | null;
+}
+
+export interface JailActivationResponse {
+  /** Name of the affected jail. */
+  name: string;
+  /** New activation state: true after activate, false after deactivate. */
+  active: boolean;
+  /** Human-readable result message. */
+  message: string;
+}