VL: Überarbeiten weiterer Einheiten

[cagix]

Vorhandene Lektionen (Markdown-Dateien), die nicht im Sommer 2026 angefasst und überarbeitet wurden:

comm -23 \
  <(git ls-files '*.md' | sort) \
  <(git log a3071e9..HEAD --name-only --pretty=format: -- '*.md' | sort -u)

• (!!) admin/exams.md
• (??) lecture/git/git5-bisect.md
• (??) lecture/java-classic/annotations.md
• (??) lecture/java-classic/collections.md
• lecture/java-classic/configuration.md
• (!!) lecture/java-classic/enums.md
• lecture/java-classic/reflection.md
• lecture/java-classic/serialisation.md
• lecture/java-classic/threads1-basics.md
• lecture/java-classic/threads2-synchronisation.md
• lecture/java-classic/threads3-highlevel.md
• (??) lecture/pattern/factory-method.md
• lecture/pattern/flyweight.md
• (??) lecture/pattern/singleton.md
• (??) lecture/pattern/strategy.md
• lecture/pattern/type-object.md
• (??) lecture/quality/tdd.md
• lecture/tooling/ant.md