fix(conversations): reject blank archive ids

[aiirvizionz]

Summary

• Trim archive and unarchive conversationId values before passing them to RPC calls.
• Return the existing missing-id 400 response for whitespace-only ids.
• Add regression coverage for archive/unarchive blank ids and trimmed valid ids.

Validation

• git diff --check
• node node_modules\vitest\vitest.mjs run --config %TEMP%\qryptchat-vitest-minimal.config.mjs "src/app/api/conversations/archive/route.test.js" (3 tests passed)

I used the same temporary minimal Vitest config needed locally because the repo's default Vitest config currently fails to load through the installed Vite/plugin combination; no dependency files were modified.