fix: show limitations for full-support entries; update BigQuery and Databricks data

- Fix combine() to preserve limitations when both sides are full — they
  were silently discarded, making full+limitations entries unexpandable
  (affected Snowflake Glue/REST/S3 Tables/Unity and the new Databricks
  Hive entry)
- Add chevron indicator (›/▾) to expandable rows so users can see the
  pane is clickable; chevron rotates on expand
- Databricks Hive: add deprecation note (new accounts after Dec 18,
  2025 have no Hive Metastore access)
- BigQuery REST: add Snowflake + Databricks to cross-engine preview
  list; add specific REST catalog table limitations (no views, no
  metadata tables, no clustering, no renaming); add source URL

Author: b-per

src/data/compatibility.ts

@@ -47,11 +47,13 @@ export const engineCatalogRules: Record<EngineId, EngineRule> = {
     glue:     { support: 'none', limitations: [] },
     rest:     { support: 'partial', limitations: [
       'BigQuery manages Iceberg tables via the Lakehouse runtime catalog (formerly BigLake Metastore) — a GCP-specific managed REST endpoint, not a self-hosted open catalog',
-      'Read and write interoperability with external engines (Spark, Flink, Trino) is in preview as of April 2026 — not yet GA',
+      'Cross-engine read/write interoperability (Spark, Flink, Trino, Snowflake, Databricks) is in preview as of May 2026 — not yet GA',
       'Credential vending is supported for cross-engine access control',
+      'REST catalog tables do not support views over Iceberg, metadata tables (.snapshots, .files), clustering, or table renaming',
     ], sourceUrls: [
       'https://cloud.google.com/blog/products/data-analytics/improved-interoperability-for-your-apache-iceberg-lakehouse',
       'https://docs.cloud.google.com/lakehouse/docs/about-lakehouse-catalogs',
+      'https://cloud.google.com/blog/products/data-analytics/unveiling-new-bigquery-capabilities-for-the-agentic-era',
     ]},
     hive:     { support: 'none', limitations: [] },
     s3tables: { support: 'none', limitations: [] },
@@ -69,7 +71,9 @@ export const engineCatalogRules: Record<EngineId, EngineRule> = {
       'https://docs.databricks.com/aws/en/iceberg/',
       'https://iceberg.apache.org/docs/latest/spark-configuration/',
     ]},
-    hive:     { support: 'full', limitations: [] },
+    hive:     { support: 'full', limitations: [
+      'Hive Metastore is deprecated — new Databricks accounts created after December 18, 2025 no longer have access; Unity Catalog is the recommended replacement',
+    ] },
     s3tables: { support: 'none', limitations: [] },
     unity:    { support: 'full', limitations: [] },
     ducklake: { support: 'partial', limitations: [

src/lib/CatalogResults.svelte

@@ -20,9 +20,9 @@
 
   function combine(w: CatalogSupport, r: CatalogSupport): CatalogSupport {
     if (w.support === 'none' || r.support === 'none') return { support: 'none', limitations: [] };
-    if (w.support === 'full' && r.support === 'full') return { support: 'full', limitations: [] };
     const seen = new Set(w.limitations);
     const limitations = [...w.limitations, ...r.limitations.filter(l => !seen.has(l))];
+    if (w.support === 'full' && r.support === 'full') return { support: 'full', limitations };
     return { support: 'partial', limitations };
   }
 
@@ -101,7 +101,10 @@
           >
             <div class="catalog-row-main">
               <span class="catalog-name">{CATALOG_LABELS[catalog]}</span>
-              <span class="support-badge {supportClass(support)}">{supportLabel(support)}</span>
+              <span class="row-right">
+                <span class="support-badge {supportClass(support)}">{supportLabel(support)}</span>
+                <span class="chevron" class:open={expanded === catalog}>›</span>
+              </span>
             </div>
             {#if expanded === catalog && entry?.limitations.length}
               <ul class="limitations">
@@ -247,6 +250,25 @@
   .catalog-row.expandable { cursor: pointer; }
   .catalog-row.expandable:hover { filter: brightness(1.15); }
 
+  .row-right {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+  }
+
+  .chevron {
+    color: #555;
+    font-size: 14px;
+    line-height: 1;
+    display: inline-block;
+    transform: rotate(0deg);
+    transition: transform 0.15s, color 0.15s;
+  }
+  .chevron.open {
+    transform: rotate(90deg);
+    color: #aaa;
+  }
+
   .catalog-row-main {
     display: flex;
     justify-content: space-between;