fix(docs): repoint two SITEMAP links moved by next's docs restructure

The two streams collided without conflicting. main added a 'Pi persistent
goals' section pointing at docs/guides/{user,admin}-guide.md; next's #1210
restructure had already moved both files to docs/_old_structure/guides/.
Git merged the addition cleanly because neither side touched the other's
lines, so the break only surfaced in fleet-documentation.spec.ts.

dev-guide.md stayed at docs/guides/ and needed no change. Anchors verified
present at the new paths.

docs/SITEMAP.md

@@ -21,9 +21,9 @@
 
 ## Pi persistent goals
 
-- [Persistent goal user guide](guides/user-guide.md#pi-persistent-goals) — `/goal` commands, verification behavior, limits, compaction/resume semantics, and limitations.
+- [Persistent goal user guide](_old_structure/guides/user-guide.md#pi-persistent-goals) — `/goal` commands, verification behavior, limits, compaction/resume semantics, and limitations.
 - [Goal extension developer guide](guides/dev-guide.md#pi-persistent-goal-extension) — framework ownership, launcher ordering, lifecycle design, tests, and local Mosaic-path smoke workflow.
-- [Goal loop operations](guides/admin-guide.md#pi-goal-loop-operations) — deployment ownership, bounded settings, pause/resume procedures, and supervisor boundary.
+- [Goal loop operations](_old_structure/guides/admin-guide.md#pi-goal-loop-operations) — deployment ownership, bounded settings, pause/resume procedures, and supervisor boundary.
 - [Pi runtime reference](../packages/mosaic/framework/runtime/pi/RUNTIME.md#extensions) — deployed paths, command summary, and bounded environment settings.
 
 ## Fleet configuration management