ci: exempt Server-Side Enhancement label from stale bot (#1841)

* ci: exempt server-side-gap label from stale bot

Issues blocked on server-side REST API work have no client-side activity
to accumulate, so the stale bot would repeatedly flag them by default.
Exempt the `server-side-gap` label (used to mark issues that need a
server-side fix and cannot be resolved in TSC alone) so those items
stay open until the underlying server work lands.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fixup: use existing 'Server-Side Enhancement' label instead of new one

The repo already has a 'Server-Side Enhancement' label applied to
issues blocked on server-side REST API work (e.g. #1716, #1658, #1537,
#1508). Adding a parallel 'server-side-gap' label would have been
redundant. Point the stale-bot exemption at the existing label.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jacalata

.github/workflows/stale.yml

@@ -18,7 +18,7 @@ jobs:
         with:
           stale-issue-label: 'stale'
           stale-pr-label: 'stale'
-          exempt-issue-labels: 'good first issue,Design Proposal,in-progress'
+          exempt-issue-labels: 'good first issue,Design Proposal,in-progress,Server-Side Enhancement'
           exempt-pr-labels: 'in-progress'
 
           days-before-issue-stale: 60