Blog/compare markdown renderer truncates URLs containing a closing paren

[vivek7405]

Problem

The shared markdown renderer's inline-link regex in website/modules/blog/utils/render-post.ts (/\[([^\]]+)\]\(([^)]+)\)/) stops the URL capture at the first ). A URL that legitimately contains a closing paren, e.g. [Ruby](https://en.wikipedia.org/wiki/Ruby_(programming_language)), is truncated to https://en.wikipedia.org/wiki/Ruby_(programming_language, so both the emitted href and (after #857) the external-vs-internal new-tab decision run on the wrong URL.

Pre-existing (predates the outbound-links change in #857); surfaced during that PR's review. Low real-world impact today because all repo-authored blog/compare markdown uses paren-free URLs, but it will silently corrupt the first Wikipedia-style link anyone writes.

Design / approach

Handle balanced parens in the URL portion (CommonMark permits nested balanced parens in the destination), or at minimum accept a single level of nested (...). A pragmatic fix is a small manual scan of the destination that tracks paren depth instead of the greedy [^)]+. Keep it dependency-free (the renderer is intentionally a small regex-based util, no markdown library).

Implementation notes (for the implementing agent)

• Where: website/modules/blog/utils/render-post.ts, the inline() function, the link replace() on the /\[([^\]]+)\]\(([^)]+)\)/ regex.
• Landmine: inline() first &<>-escapes the whole string, then runs the link regex; keep that ordering. feat: link compared frameworks from the /compare pages #857 added %22 href-escaping and an external/new-tab branch on the SAME captured URL, so whatever fix lands must feed the full (untruncated) URL into both.
• Tests: add a case to website/test/ssr/compare-ssr.test.ts (or a blog render test) for a URL with a nested ).
• No em-dashes / invariant-11 punctuation in new prose.

Acceptance criteria

• [t](https://host/a_(b)) renders href="https://host/a_(b)" (full URL, not truncated).
• The external/new-tab decision uses the full URL.
• Test covers a paren-containing URL, with a counterfactual.