Adds a failing regression test that reproduces the write tool hang
reported in #22872. The write tool calls lsp.touchFile + lsp.diagnostics
to enrich its output; if a matching LSP server spawns but never responds
to the initialize request, the tool blocks on LSPClient.create's 45s
withTimeout.
The test configures a fake LSP server (hanging-lsp-server.js) that
swallows every message and never replies, asserts the file is still
written correctly, and checks the tool returns within 10s. On dev today
the assertion fails with ~45s actual, proving the hang. The fix should
make this green by bounding the diagnostic-enrichment tail.
4c52af2a65