Add jdt:// URI rewriting for documentation responses

[tartarughina]

Extends the LSP proxy to resolve jdt:// URIs embedded inside documentation responses, and applies a few performance optimizations along the way.

Problem

Zed cannot open jdt:// URIs. The proxy already rewrites them in textDocument/definition/typeDefinition/implementation responses by fetching the decompiled class via java/classFileContents and exposing it as a temp file. However, JDTLS also embeds jdt:// URIs inside Javadoc markdown (e.g. ArrayList) returned by textDocument/hover, textDocument/signatureHelp, and completionItem/resolve. Those links were unreachable from Zed.

Changes

Feature: rewrite jdt:// URIs in documentation responses

• Track request IDs for textDocument/hover, textDocument/signatureHelp, and completionItem/resolve on the inbound path.
• On the matching response, recursively scan all strings in result for embedded jdt:// URIs, resolve each unique one through the existing resolve_jdt_uri cache, and replace the occurrences with the corresponding file:// URI in-place.
• Deduplication within a response (collect_jdt_uris) and the on-disk cache (path.exists() short-circuit in resolve_jdt_uri) prevent redundant java/classFileContents calls.

Test

• Run just proxy-install from the extension directory
• Move the new proxy from .../Zed/extensions/work/java/proxy-bin to the most recent version of the proxy ie. mv java-lsp-proxy v6.8.13.1
• Restart the language server from Zed