docs: consolidate roadmaps and update architecture documentation

Replaced fragmented roadmaps with a single MASTER_ROADMAP for Q1 2026 as the authoritative source. Deprecated outdated roadmap files and updated Architect playbook to reflect new ownership and delegation responsibilities. Introduced architecture improvement proposals and added related documents for enhanced collaboration and knowledge sharing.

core/core-utils/src/commonMain/kotlin/at/mocode/core/sync/Syncable.kt

@@ -0,0 +1,9 @@
+package at.mocode.core.sync
+
+/**
+ * Interface for entities that can be synchronized.
+ */
+interface Syncable {
+    val id: String
+    val lastModified: Long
+}