feat: uwf cas put-text for storing plain text in CAS

- Register built-in text schema ({type: 'string'}) alongside workflow schemas
- Add cmdCasPutText command: uwf cas put-text <text>
- Update CLI reference in workflow-util
- Update solve-issue.yaml procedure to use put-text

Refs #380

packages/cli-workflow/src/cli.ts

@@ -7,6 +7,7 @@ import {
   cmdCasGet,
   cmdCasHas,
   cmdCasPut,
+  cmdCasPutText,
   cmdCasRefs,
   cmdCasReindex,
   cmdCasSchemaGet,
@@ -295,6 +296,17 @@ cas
     });
   });
 
+cas
+  .command("put-text")
+  .description("Store a plain text string, print its hash")
+  .argument("<text>", "Text content to store")
+  .action((text: string) => {
+    const storageRoot = resolveStorageRoot();
+    runAction(async () => {
+      writeOutput(await cmdCasPutText(storageRoot, text));
+    });
+  });
+
 cas
   .command("has")
   .description("Check if a hash exists")