0.1.0:2 - remove '<spark-user>' default everywhere (it's Alice's username, not factory)

Per user correction: '<spark-user>' is not the DGX Spark factory default. Generic-ize:
- configureSparks: no default user; placeholder 'your SSH username'
- sparkConfig schema: empty string defaults
- main.ts env fallback: empty
- showPublicKey: drop the '<spark-user>' fallback; skip Spark if user not configured
- Update feedback memory with the correction

package/startos/versions/v0_1_0.ts

@@ -1,10 +1,10 @@
 import { VersionInfo, IMPOSSIBLE } from '@start9labs/start-sdk'
 
 export const v0_1_0 = VersionInfo.of({
-  version: '0.1.0:1',
+  version: '0.1.0:2',
   releaseNotes: {
     en_US:
-      'Generic placeholders in Configure Sparks; Show Public Key emits a ready-to-paste install command; dashboard shows the OpenAI-compatible base URL + current model ID with one-click copy and a curl example.',
+      'Fully generic SSH user fields (no suggested default); generic host placeholders in Configure Sparks; Show Public Key emits a ready-to-paste install command using your configured hostnames; dashboard shows the OpenAI-compatible base URL + current model ID with one-click copy and a curl example.',
   },
   migrations: {
     up: async ({ effects }) => {},