[paoloredis]

The RedisVL docs (since upstream v0.21.0) use mermaid diagrams, which were both breaking the sync build and, once building, silently dropped. This wires up end-to-end mermaid support without touching generated markdown (the sync workflow regenerates that).

• workflow: install sphinxcontrib-mermaid so conf.py's extensions import succeeds and sphinx-build no longer aborts.
• redisvl_docs_sync.py: add preserve_mermaid_fences(), run before sphinx_build. It strips "mermaid" from conf.py's myst_fence_as_directive so mermaid fences pass through as plain code blocks instead of being converted to a mermaid node that sphinx_markdown_builder drops.
• layouts: render fenced mermaid client-side at full column width; use mermaid's default font (a custom font mis-sized sequence-diagram boxes and overflowed labels); restore the default pale-yellow subgraph cluster styling to match the upstream docs.

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Note

Low Risk
Changes are limited to the RedisVL docs sync pipeline and Hugo mermaid presentation; no auth, data, or core app logic.

Overview
Fixes RedisVL doc sync for upstream mermaid diagrams (v0.21.0+): the workflow now installs sphinxcontrib-mermaid so Sphinx can import upstream conf.py, and preserve_mermaid_fences() in redisvl_docs_sync.py removes "mermaid" from myst_fence_as_directive before build so fences stay as plain ```mermaid blocks instead of being dropped by sphinx_markdown_builder.

On the Hugo side, mermaid code blocks default to full column width, client rendering uses mermaid’s default font (avoids sequence-diagram label overflow), adds SVG width scaling, and restores pale-yellow subgraph cluster styling to match upstream docs.

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[github-actions]

DOC-6808

[jit-ci]

🛡️ Jit Security Scan Results

✅ No security findings were detected in this PR

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