fix: reset correct loading state after manual transaction processing

The finally block was resetting runningTestTransaction instead of
processingSpecificTransaction, causing the button to stay in loading
state after processing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

static/js/index.js

@@ -670,7 +670,7 @@ window.app = Vue.createApp({
       } catch (error) {
         LNbits.utils.notifyApiError(error)
       } finally {
-        this.runningTestTransaction = false
+        this.processingSpecificTransaction = false
       }
     },