fix: make blank LangSmith input disable tracing (#54)

A LANGCHAIN_TRACING_V2=true saved by an earlier setup survived in
~/.openwiki/.env when the user later left the LangSmith prompt blank,
because saveOpenWikiEnv merges updates and never clears the flag.
Blank input now explicitly writes LANGCHAIN_TRACING_V2=false.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: Brace Sproul <braceasproul@gmail.com>

Author: 3 people

src/credentials.tsx

@@ -401,6 +401,11 @@ export function InitSetup({
         if (nextLangSmithKey.length > 0) {
           updates.LANGCHAIN_PROJECT = "openwiki";
           updates.LANGCHAIN_TRACING_V2 = "true";
+        } else {
+          // Blank input must act as an off switch: without this, a
+          // LANGCHAIN_TRACING_V2=true saved by an earlier setup stays in
+          // ~/.openwiki/.env and tracing silently remains enabled.
+          updates.LANGCHAIN_TRACING_V2 = "false";
         }
       }