Facade: split subsystem into one class per file, sync post code blocks to Java 25, add README mapping

02-structural/facade/README.md

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+# Facade Design Pattern — Java Example
+
+**Pattern:** Structural → Facade
+**Article:** https://ankurm.com/facade-design-pattern-java/
+
+## What this example shows
+
+A video-conversion subsystem (`VideoFile`, `Codec`, `MPEG4CompressionCodec`, `OggCompressionCodec`, `CodecFactory`, `BitrateReader`, `AudioMixer`) is wrapped behind one class, `VideoConversionFacade`, that exposes a single `convertVideo()` method. Callers never touch the six subsystem classes directly, but they remain public and usable on their own for advanced use cases.
+
+## How to run
+
+```bash
+javac facade/*.java -d out/facade
+java -cp out/facade facade.Main
+```
+
+Requires Java 25.
+
+## Post Section ↔ File Mapping
+
+| Post Section | File(s) |
+|---|---|
+| The Subsystem (Complex, But Unchanged) — VideoFile | `VideoFile.java` |
+| The Subsystem (Complex, But Unchanged) — Codec interface | `Codec.java` |
+| The Subsystem (Complex, But Unchanged) — Concrete Codecs | `MPEG4CompressionCodec.java`, `OggCompressionCodec.java` |
+| The Subsystem (Complex, But Unchanged) — CodecFactory | `CodecFactory.java` |
+| The Subsystem (Complex, But Unchanged) — BitrateReader | `BitrateReader.java` |
+| The Subsystem (Complex, But Unchanged) — AudioMixer | `AudioMixer.java` |
+| The Facade | `VideoConversionFacade.java` |
+| Client Code: One Line | `Main.java` |
+
+Note: the SLF4J `LoggerFactory`, JDBC `DriverManager`, and Spring `JdbcTemplate` snippets under "Facade in the JDK and Real Frameworks" are illustrative only — they are not part of this repository's runnable example.
+
+Article: https://ankurm.com/facade-design-pattern-java/
+All patterns: https://ankurm.com/design-patterns-java/