chore: upgrade StudioBridge v2.1.2 -> v2.1.3, add persistent-folder creation, update runbook

- Rebuild StudioBridge-2.1.3.jar from latest upstream (v2.1.3) and deploy to portable-dist
- Add ensurePersistentDirectories() so the app creates ~/.studio-bridge and Profiles at startup (GUI + --sendonly)
- Bundle full StudioBridge source under StudioBridge-src/ (with rebuild-jar.bat)
- Update launchers (Launch-StudioBridge.bat, portable-dist/StudioBridge.bat) to v2.1.3
- Add check-update.ps1 and UPDATE.md for the step-by-step update runbook
- Update README (v2.1.3, persistent data + updating sections)
- Ignore StudioBridge-src/target/ build output

StudioBridge-src/.github/FUNDING.yml

@@ -0,0 +1,15 @@
+# These are supported funding model platforms
+
+github: # Replace with up to 4 GitHub Sponsors-enabled usernames e.g., [user1, user2]
+patreon: # Replace with a single Patreon username
+open_collective: # Replace with a single Open Collective username
+ko_fi: # Replace with a single Ko-fi username
+tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel
+community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
+liberapay: # Replace with a single Liberapay username
+issuehunt: # Replace with a single IssueHunt username
+lfx_crowdfunding: # Replace with a single LFX Crowdfunding project-name e.g., cloud-foundry
+polar: # Replace with a single Polar username
+buy_me_a_coffee: Rdiger36
+thanks_dev: # Replace with a single thanks.dev username
+custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']