fix(dashboard): restore shift-click suggestion submit

Default domain was retired slug "custodian", so POST /technical-debt/
returned 422 and the modal failed after open. Use infotech, resolve
apiBase like config.js, and surface API error detail in the toast.

dashboard/observablehq.config.js

@@ -10,7 +10,9 @@ const _configDir = dirname(fileURLToPath(import.meta.url));
 const _modalScript = readFileSync(
   join(_configDir, "src/components/improvement-modal.js"), "utf-8"
 )
-  .replace(/^export function /gm, "function ")   // strip ES module export
+  // Strip ES module exports so the file can run as a plain <script>.
+  .replace(/^export function /gm, "function ")
+  .replace(/^export const /gm, "const ")
   + "\ninitImprovementModal();\n";               // auto-initialise
 
 export default {