FN-6440: replace dashboard skip-list placeholders

Dashboard curated-gate skip-list entries now point to actionable tracking work.

- Replace placeholder FN-TBD references with concrete Fusion task IDs grouped by affected dashboard area.
- Document the requirement that skip-list reasons cite real tracking tasks unless entries are removed after rescue.
- Preserve the standalone build-output exception while making the remaining skip-list ownership actionable.

Files changed:
 docs/testing.md                             |  1 +
 scripts/lib/dashboard-curated-skiplist.json | 66 ++++++++++++++---------------
 2 files changed, 34 insertions(+), 33 deletions(-)

Fusion-Task-Id: FN-6440
Fusion-Task-Lineage: abf1cef2-8199-4746-b8ec-8b5487eb1ecc

docs/testing.md

@@ -101,6 +101,7 @@ every entry needs a non-empty `reason` (empty reasons are rejected). Skip-list p
   that is pre-existing-failing orphans (tests that were never executed in CI and
   fail in isolation) and `build-output.test.ts` (runs standalone via `test:build`
   after a Vite build). Each carries a one-line reason.
+- <!-- FNXC:DashboardTesting 2026-06-14-08:00: Skip-listed dashboard tests need actionable ownership; placeholder IDs block rescue/delete follow-through, so every non-standalone reason cites a concrete Fusion tracking task. --> Every skip-list `reason` for a pre-existing failing/orphaned test must reference a concrete `FN-NNNN` tracking task; if the test is rescued, remove the entry instead of leaving a tracking placeholder.
 - To remove a file from the skip-list: fix the test, confirm it passes under its
   project, delete the skip-list entry. The backfill lane then executes it.
 - The skip-list is shared verbatim with `vitest.config.ts`, which excludes the same