Correct the JDK claim, and finish the @UnstableApi propagation

Two things the first pass got wrong.

CLAUDE.md said "use a JDK 17-21, AGP 9 does not support 25+". That was carried
over from the sibling repo and is not true here: gradle-daemon-jvm.properties
pins toolchainVersion=25, so Gradle provisions and runs the daemon on Java 25
whatever JAVA_HOME says -- JAVA_HOME only picks the launcher. `gradlew --version`
prints both, and shows them differing on this machine right now. It also means
CI's java-version: '17' is not the JDK that compiles anything, and that the
daemon JVM is the same on a laptop as on a runner, which is a better guarantee
than the one the file claimed.

Marking ConversionDependencies @UnstableApi propagates to its callers, and
FakeFailures in androidTest calls it. That is a warning rather than an error in
Kotlin, and lint does not read the androidTest source set, so the previous
commit compiled clean while leaving one file inconsistent with the very pattern
it described. Marked now.

Left alone deliberately: gradlew.bat. The new `*.bat text eol=crlf` attribute
governs how it is checked out from here on, which is the point of adding it,
and the file already has CRLF in both the tree and the index. Rewriting the
stored bytes of the wrapper script to prove the attribute works is not this
branch's business.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/src/androidTest/java/org/libremediaconverter/fallback/FakeFailures.kt

@@ -2,6 +2,7 @@ package org.libremediaconverter.fallback
 
 import android.content.Context
 import android.net.Uri
+import androidx.media3.common.util.UnstableApi
 import org.libremediaconverter.convert.ConversionDependencies
 import org.libremediaconverter.convert.HardwareTranscoder
 import org.libremediaconverter.convert.OutputPublisher
@@ -17,6 +18,7 @@ import java.io.File
  * test run avoids. Without a way to inject failure, the branches a user meets on a bad
  * day are the ones that were never executed.
  */
+@UnstableApi
 object FakeFailures {
 
     class ExplodingHardware(private val message: String = "hardware exploded") : HardwareTranscoder {