fix(desktop): add project ProGuard rules to unblock release packaging

Compose Multiplatform 1.11.0 tightened its default ProGuard ruleset so
`proguardReleaseJars` now fails on unresolved references that 1.10.3
tolerated silently. The v1.09.0 release tag-build hit this on every
desktop leg (macOS DMG, Windows MSI, Linux DEB/RPM, Linux AppImage),
which is why only Android APKs and the macOS-arm64 / Linux Amy CLI
bundles made it onto the GitHub release.

Three groups of references were flagged:

  - Jackson kotlin-module 2.21.x value-class converters
    (`IntValueClassBoxConverter`, `ValueClassKeyDeserializer$*`, …)
    invoke `MethodHandle.invokeExact` with polymorphic signatures
    ProGuard cannot resolve against the abstract MethodHandle.
  - okhttp's optional TLS adapters (`okhttp3.internal.graal.*`,
    `BouncyCastle/Conscrypt/OpenJSSEPlatform`) reference classes from
    runtime backends that aren't on the desktop classpath; okhttp falls
    back to the JDK default in their absence.
  - JNA's `com.sun.jna.internal.Cleaner` inner classes touch synthetic
    `access$N` accessors that ProGuard's class-member analysis cannot
    follow.

Add `desktopApp/compose-rules.pro` with `-dontwarn` rules for each
bucket and wire it through `compose.desktop.application.buildTypes
.release.proguard.configurationFiles`. Verified locally by re-running
`:desktopApp:proguardReleaseJars` (now BUILD SUCCESSFUL) and
`:desktopApp:packageReleaseDeb` (gets past ProGuard; only fails on the
sandbox missing `fakeroot`, which CI installs in the existing
"Install RPM tooling" step).

desktopApp/build.gradle.kts

@@ -129,6 +129,15 @@ compose.desktop {
                 rpmPackageVersion = appVersion.replace("-", "~")
             }
         }
+
+        // Compose Multiplatform 1.11.0 tightened the default ProGuard rules so
+        // unresolved references in transitive deps (Jackson kotlin-module value
+        // classes, okhttp's optional TLS adapters, JNA cleaner internals) now
+        // fail `proguardReleaseJars`. Project-level rules below add the missing
+        // `-dontwarn` directives.
+        buildTypes.release.proguard {
+            configurationFiles.from(project.file("compose-rules.pro"))
+        }
     }
 }