chore(java): consolidate mss-failsafe to single canonical copy

Replace the stale multi-module java/mss-failsafe skeleton (old user-management
prototype) with the active single-module machine-safety inspection app that was
living in its own standalone repo at the repo root.

- Remove old java/mss-failsafe/ multi-module tree (mss, userdata, userManagement,
  mssfailsafe.datalayer, mssfailsafeWeblayer) incl. committed build artifacts
- Add the active app (PrimeFaces 11 / JSF 2.3 / Hibernate 5.6 / iText / POI)
  flattened into java/mss-failsafe/ as the only mss-failsafe in git
- Working tree captured = master tip 2a142b5 + in-progress uncommitted work
  (incl. .github/*.instructions.md AI-context files)
- Archive the standalone repo's 33-commit history in GIT_HISTORY_ARCHIVE.md
  since its .git was not migrated

This is the source of truth / base for the upcoming upgraded rewrite.

java/mss-failsafe/.github/extend_project.instructions.md

@@ -0,0 +1,33 @@
+# Extend Project Instructions
+
+## Pattern
+Entity -> Manager -> Controller -> XHTML -> Navigation
+
+## Steps (Template)
+1. Entity: @Entity extends AbstractEntity
+2. Manager: @Stateless extends AbstractManager<Entity>
+3. Controller: @Named + Scope extends AbstractController<Entity>
+4. UI: xhtml mit #{controller}
+5. Tests: CRUD + Spezialmethoden
+
+## Fake IDs
+- Neue Objekte in Collections: negative ID (createFakeID)
+- Vor Persist: setId(null)
+
+## Klonen
+- Quelle laden & initialisieren
+- Copy-Konstruktor
+- Child IDs null
+
+## Checklist
+- [ ] Named Queries falls benötigt
+- [ ] Logging bei Fehlern
+- [ ] @Transactional bei Schreibmethoden
+- [ ] Keine System.out
+
+## Common Pitfalls
+- LazyInitializationException -> refresh
+- Vergessen negative IDs zurückzusetzen -> Persist fehlschlägt
+
+---
+Aktualisiert: 2025-10-20