Boxel UI build & test-app refactor

[ef4]

This updates boxel-ui to the newest v2 addon blueprint. That includes bringing the tests into a single package so, no more separate addon and test-app workspace packages.

• there are breaking upgrades to ember-basic-dropdown and power-select in here that need some minor followup
• not all styles are working the same yet in the tests-app
• the deploy code for the test app needs to be restored

[github-actions]

Realm Server Test Results

0 tests  ±0   0 ✅ ±0   0s ⏱️ ±0s
0 suites ±0   0 💤 ±0 
1 files   ±0   0 ❌ ±0 

Results for commit 4f9f7d3. ± Comparison against earlier commit 433d435.

[github-actions]

Grafana preview

Preview deployed for 1 dashboard in the staging Grafana.
Cross-dashboard drill-throughs still point at the canonical staging dashboards.

• Folder: Preview – PR #5007: Boxel Status

Dashboards:

• [PR #5007] Worker

Preview is torn down automatically when this PR is closed or merged.

(Run: https://github.com/cardstack/boxel/actions/runs/28618827525)

[github-actions]

Observability diff (vs staging)

Show diff

diff --git a/tmp/remote-canon.cZspTP/dashboards/boxel-status/service-worker.json b/tmp/committed-canon.oXPzKr/dashboards/boxel-status/service-worker.json
index 14d31ea..cdcc357 100644
--- a/tmp/remote-canon.cZspTP/dashboards/boxel-status/service-worker.json
+++ b/tmp/committed-canon.oXPzKr/dashboards/boxel-status/service-worker.json
@@ -1811,7 +1811,7 @@
         {
           "hide": 2,
           "name": "env",
-          "query": "staging",
+          "query": "__ENV__",
           "skipUrlSync": true,
           "type": "constant"
         }

(Run: https://github.com/cardstack/boxel/actions/runs/28618827581)