Fix search navigation to legacy documentation URLs

[rmcdaniel]

Problem

Refs #131. Live Waterline search results still point to /docs/2.0/ paths. Those paths have redirect HTML but no React route, so client-side search navigation renders Page Not Found.

Change

Use Docusaurus's built-in replaceSearchResultPathname to remove only the former /docs/2.0/ prefix. Preserve current paths, 1.x routes, queries and anchors. No new dependencies or custom search UI.

A focused test exercises the theme's actual configuration normalization, not just the raw JavaScript regexp; Docusaurus escapes string matchers, so the matcher must be a RegExp. The test is part of the existing build command.

Validation

• Reproduced the live browser failure before changing configuration.
• All 47 unique paths from the live Waterline query have canonical counterparts in the current build.
• Production build and link checks pass.
• Seven route assertions pass through actual Docusaurus normalization. Substituting the incorrectly escaped string matcher reproduces the failure.
• Desktop/mobile browser validation in progress.

This repairs the legacy-prefix navigation failure, not index freshness. The index still includes old headings/prerelease titles and lacks a direct current Waterline API result. #131 remains open for that separate outcome.

[rmcdaniel]

Focused browser qualification passed at candidate 7f4c28a2f2, with production build assets served under the production origin and the real public search response.

At 1280x800 and 390x844:

• waterline -> Cancel and Terminate renders the canonical page, not Page Not Found.
• waterline -> Monitoring renders the canonical page.
• Waterline Operator API Reference -> the indexed Run And Operate category works; its current Waterline API link opens the reference.

The first external-navigation setting and an incorrectly string-encoded replacement were rejected during browser/normalization checks before merge. The final change uses the built-in RegExp replacement, with seven build-time regression assertions. No library or custom navigation layer was added.

The #installing-waterline result is still an obsolete indexed heading, and the direct API page is not indexed. These remain the index-freshness work in #131, not claimed repaired by this PR.

[rmcdaniel]

Deployed and verified live on September 12 at 13:59 UTC.

• Merged commit: e77234f0d000febe244c48ba6a0a12751f95a0cd.
• Pages publication succeeded; Pages build 3760a967a1da2e9f055bd881c4ee2477a995367c is built.
• Unintercepted live browser checks at 1280x800 and 390x844 passed: search -> Cancel and Terminate, search -> Monitoring, search -> Run And Operate -> Waterline Operator API Reference.
• Current main qualification, protocol and boundary checks all passed.
• No SDK/runtime artifact or Cloud deployment is needed for this change.

The stale index headings and missing direct reference result remain open in #131. This is a delivered navigation fix, not a claim that the index has been refreshed.