Update Linear Integration extension to v0.7.0 (#3089)

Update linear extension submitted by @ashbrener:
- extensions/catalog.community.json (version, download_url, updated_at)
- docs/community/extensions.md community extensions table (no display fields changed)

Closes #3087

Assisted-by: GitHub Copilot (model: claude-sonnet-4.6, autonomous)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

extensions/catalog.community.json

@@ -1,6 +1,6 @@
 {
   "schema_version": "1.0",
-  "updated_at": "2026-06-18T00:00:00Z",
+  "updated_at": "2026-06-22T00:00:00Z",
   "catalog_url": "https://raw.githubusercontent.com/github/spec-kit/main/extensions/catalog.community.json",
   "extensions": {
     "aide": {
@@ -1540,8 +1540,8 @@
       "id": "linear",
       "description": "Mirror spec-kit feature directories into Linear (filesystem → Linear, reconcile-based, unidirectional).",
       "author": "Ash Brener",
-      "version": "0.6.0",
-      "download_url": "https://github.com/ashbrener/spec-kit-linear-sync/archive/refs/tags/v0.6.0.zip",
+      "version": "0.7.0",
+      "download_url": "https://github.com/ashbrener/spec-kit-linear-sync/archive/refs/tags/v0.7.0.zip",
       "repository": "https://github.com/ashbrener/spec-kit-linear-sync",
       "homepage": "https://github.com/ashbrener/spec-kit-linear-sync",
       "documentation": "https://github.com/ashbrener/spec-kit-linear-sync/blob/main/README.md",
@@ -1568,7 +1568,7 @@
       "downloads": 0,
       "stars": 0,
       "created_at": "2026-06-01T00:00:00Z",
-      "updated_at": "2026-06-17T00:00:00Z"
+      "updated_at": "2026-06-22T00:00:00Z"
     },
     "loop": {
       "name": "Loop Engineering",