Refactor large Kotlin source files

- Split core game models from sandbox engine, native level setup, and repo state saving.

- Move app overlays and completion helpers out of GitHugApp.

- Extract the terminal special key bar into its own component.

app/src/main/java/solutions/tretter/githugandroid/RepoStateSaver.kt

@@ -0,0 +1,68 @@
+package solutions.tretter.githugandroid
+
+import androidx.compose.runtime.saveable.listSaver
+
+val RepoStateSaver = listSaver<RepoState, Any>(
+    save = { state ->
+        listOf(
+            state.initialized,
+            state.headBranch,
+            state.files.flatMap { listOf(it.name, it.content, it.staged.toString(), it.tracked.toString(), it.deleted.toString()) },
+            state.commits.flatMap { listOf(it.id, it.message) },
+            state.branches.flatMap { listOf(it.key, it.value.toString()) },
+            state.currentDir,
+            state.tags,
+            state.remotes.flatMap { listOf(it.key, it.value) },
+            state.config.flatMap { listOf(it.key, it.value) },
+            state.stashes,
+            state.fetchedBranches.toList(),
+            state.pushedBranches.toList(),
+            state.pushedTags.toList(),
+            state.submodules.flatMap { listOf(it.key, it.value) },
+            state.maintenanceActions.toList(),
+        )
+    },
+    restore = { saved ->
+        val initialized = saved[0] as Boolean
+        val headBranch = saved[1] as String
+        val fileParts = saved[2] as List<*>
+        val commitParts = saved[3] as List<*>
+        val branchParts = saved[4] as List<*>
+        val tags = saved[6] as List<*>
+        val remoteParts = saved[7] as List<*>
+        val configParts = saved.getOrNull(8) as? List<*> ?: emptyList<Any>()
+        val stashes = saved.getOrNull(9) as? List<*> ?: emptyList<Any>()
+        val fetchedBranches = saved.getOrNull(10) as? List<*> ?: emptyList<Any>()
+        val pushedBranches = saved.getOrNull(11) as? List<*> ?: emptyList<Any>()
+        val pushedTags = saved.getOrNull(12) as? List<*> ?: emptyList<Any>()
+        val submoduleParts = saved.getOrNull(13) as? List<*> ?: emptyList<Any>()
+        val maintenanceActions = saved.getOrNull(14) as? List<*> ?: emptyList<Any>()
+        RepoState(
+            initialized = initialized,
+            headBranch = headBranch,
+            files = fileParts.chunked(if (fileParts.size % 5 == 0) 5 else 4).map {
+                GitFile(
+                    name = it[0] as String,
+                    content = it[1] as String,
+                    staged = (it[2] as String).toBoolean(),
+                    tracked = (it[3] as String).toBoolean(),
+                    deleted = (it.getOrNull(4) as? String)?.toBoolean() ?: false,
+                )
+            },
+            commits = commitParts.chunked(2).map {
+                CommitNode(it[0] as String, it[1] as String)
+            },
+            branches = branchParts.chunked(2).associate { (it[0] as String) to (it[1] as String).toInt() },
+            currentDir = saved[5] as String,
+            tags = tags.filterIsInstance<String>(),
+            remotes = remoteParts.chunked(2).associate { (it[0] as String) to (it[1] as String) },
+            config = configParts.chunked(2).associate { (it[0] as String) to (it[1] as String) },
+            stashes = stashes.filterIsInstance<String>(),
+            fetchedBranches = fetchedBranches.filterIsInstance<String>().toSet(),
+            pushedBranches = pushedBranches.filterIsInstance<String>().toSet(),
+            pushedTags = pushedTags.filterIsInstance<String>().toSet(),
+            submodules = submoduleParts.chunked(2).associate { (it[0] as String) to (it[1] as String) },
+            maintenanceActions = maintenanceActions.filterIsInstance<String>().toSet(),
+        )
+    }
+)