feat(12-01): add semantic token classes to all step h2 headings

- BackendSelectionStep h2: text-2xl font-bold text-on-surface mb-2
- RemoteConfigStep h2: text-2xl font-bold text-on-surface mb-2
- DeploymentStep h2: text-2xl font-bold text-on-surface mb-2
- ReviewStep h2: text-2xl font-bold text-on-surface mb-2

src/components/wizard/BackendSelectionStep.tsx

@@ -62,7 +62,7 @@ export function BackendSelectionStep() {
 
   return (
     <div>
-      <h2>Step 1: Select Backend</h2>
+      <h2 className="text-2xl font-bold text-on-surface mb-2">Step 1: Select Backend</h2>
       <p className="text-sm text-on-surface-variant mt-1 mb-4">
         Name your remote and pick the cloud storage provider you want to connect to.
         Your choice determines which credentials are required in the next step.

src/components/wizard/DeploymentStep.tsx

@@ -21,7 +21,7 @@ export function DeploymentStep() {
 
   return (
     <div>
-      <h2>Step 3: Deployment Options</h2>
+      <h2 className="text-2xl font-bold text-on-surface mb-2">Step 3: Deployment Options</h2>
       <p className="text-sm text-on-surface-variant mt-1 mb-4">
         Choose how the generated config gets deployed to the target machine and which deployment
         script formats to produce.

src/components/wizard/RemoteConfigStep.tsx

@@ -62,7 +62,7 @@ export function RemoteConfigStep() {
 
   return (
     <div>
-      <h2>Step 2: Configure {backendLabel[backendType]}</h2>
+      <h2 className="text-2xl font-bold text-on-surface mb-2">Step 2: Configure {backendLabel[backendType]}</h2>
       <p className="text-sm text-on-surface-variant mt-1 mb-4">
         Enter the credentials for your selected backend. These values are written directly into the
         generated rclone.conf and are never sent to any server.

src/components/wizard/ReviewStep.tsx

@@ -72,7 +72,7 @@ export function ReviewStep() {
 
   return (
     <div>
-      <h2>Step 4: Review &amp; Download</h2>
+      <h2 className="text-2xl font-bold text-on-surface mb-2">Step 4: Review &amp; Download</h2>
       <p className="text-sm text-on-surface-variant mt-1 mb-4">
         Review your generated files and download them. Acknowledge the security notice before
         copying or downloading credentials.