fix: apply the review items for #744 at merge

Classify OpenSSL and LibreSSL's SSL_connect errors as unreachable again (`_` is a
word character, so \bssl\b missed them and the user read the temp directory as the
reason), point a cases-folder refusal at Clone Repo instead of Create New, and move
the mechanism and history out of CLAUDE.md into architecture-invariants.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/web/routes/case-routes.ts

@@ -727,6 +727,7 @@ export function registerCaseRoutes(
           home: homedir(),
           dataDir: getDataDir(),
           casesDirs: [...new Set([casesDir, resolveCasesDir()])],
+          casesDirAdvice: 'clone there without a custom folder',
         });
         if (!prepared.ok) {
           reply.code(