Pin Quartz docs build to v4.5.2 (v5.0.0 broke build)

The Dagger build_docs pipeline cloned Quartz from the default branch
unpinned. Quartz v5.0.0 restructured its config layout (.quartz/plugins,
../quartz imports), breaking the docs build against the existing
quartz.config.ts / quartz.layout.ts. Pin the clone to the last v4
release (v4.5.2) so generated projects build cleanly.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.dagger/src/project_template_ci/main.py

@@ -20,6 +20,10 @@ class ProjectTemplateCi:
                     "git",
                     "clone",
                     "--depth=1",
+                    # Pin to last v4 release. v5.0.0 restructured config
+                    # layout (.quartz/plugins, ../quartz imports) and breaks
+                    # our quartz.config.ts/quartz.layout.ts.
+                    "--branch=v4.5.2",
                     "https://github.com/jackyzha0/quartz.git",
                     "/tmp/quartz",
                 ]