Implement SSH port forwarding and improve jump host UI

Port Forwarding (new):
- Add PortForward model with local/remote direction, bind/dest addresses
- Implement ForwardManager in sshclient/portforward.go with full
  bidirectional tunnel support for both local and remote forwarding
- Integrate ForwardManager into SSH client lifecycle (auto-start on
  connect, clean shutdown on close)
- Add session manager methods: ListPortForwards, StartPortForward,
  StopPortForward with event emission
- Add API surface: ListPortForwards, StartPortForward, StopPortForward
- Add validation for port-forward rules in ValidateSSHConfig
- Add port forwarding section to profile editor with direction, bind/dest
  host/port, label, and enable toggle
- Add frontend event handling for forward:started/stopped/error
- Style port-forward rows with charcoal card design matching jump hosts

Jump Host UI improvements:
- Add private key path field to jump host editor rows
- Collect privateKeyPath in form value collection
- Restyle jump host rows as two-line cards with clear field grouping

frontend/wailsjs/go/api/Service.d.ts

@@ -47,6 +47,8 @@ export function ListFavourites():Promise<Array<models.Profile>>;
 
 export function ListKnownHosts():Promise<Array<models.KnownHost>>;
 
+export function ListPortForwards(arg1:string):Promise<Array<models.PortForward>>;
+
 export function ListProfiles():Promise<Array<models.Profile>>;
 
 export function ListProfilesByFolder(arg1:string):Promise<Array<models.Profile>>;
@@ -91,6 +93,10 @@ export function SetFavourite(arg1:string,arg2:boolean):Promise<void>;
 
 export function SetProfileSecret(arg1:string,arg2:string,arg3:string):Promise<void>;
 
+export function StartPortForward(arg1:string,arg2:models.PortForward):Promise<void>;
+
+export function StopPortForward(arg1:string,arg2:string):Promise<void>;
+
 export function TestConnection(arg1:string,arg2:number):Promise<Record<string, any>>;
 
 export function UnlockSecretStore(arg1:string):Promise<void>;