fix: allow suffix text after '## Slices' heading in roadmap parser (#924) (#936)

The regex required exactly '## Slices' with nothing after. If an agent
renamed it (e.g. '## Slices (generate flow — first batch)'), the parser
returned zero slices, blocking auto-mode.

Changed /^## Slices\s*$/m to /^## Slices\b.*$/m — word boundary ensures
'Slices' is complete, .* allows any trailing text.

src/resources/extensions/gsd/roadmap-slices.ts

@@ -41,7 +41,7 @@ export function expandDependencies(deps: string[]): string[] {
 }
 
 function extractSlicesSection(content: string): string {
-  const headingMatch = /^## Slices\s*$/m.exec(content);
+  const headingMatch = /^## Slices\b.*$/m.exec(content);
   if (!headingMatch || headingMatch.index == null) return "";
 
   const start = headingMatch.index + headingMatch[0].length;