fix: keep formatClaudeStreamLine internal to avoid ESM hot-reload link failure (FAR-32)

Exposing formatClaudeStreamLine at the package root caused Paperclip reinstalls
to fail with "'./cli/index.js' does not provide an export named
'formatClaudeStreamLine'".  The host process caches child ESM module records
across reinstalls; linking the new dist/index.js re-export against the cached
old dist/cli/index.js fails.

The symbol is only used internally by server/execute.ts (which imports from
./cli/format-event.js directly), so drop the public re-export.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/cli/index.ts

@@ -1 +1 @@
-export { printClaudeStreamEvent, formatClaudeStreamLine } from "./format-event.js";
+export { printClaudeStreamEvent } from "./format-event.js";

src/index.ts

@@ -52,4 +52,4 @@ Notes:
 `;
 
 export { createServerAdapter } from "./server/index.js";
-export { printClaudeStreamEvent, formatClaudeStreamLine } from "./cli/index.js";
+export { printClaudeStreamEvent } from "./cli/index.js";