docs(shared): add strict warning headers and README to prevent out-of-sync edits

.gitignore

@@ -38,7 +38,8 @@ coverage/
 # KoalaSync Specific
 # We ignore the synced files in the extension folder to ensure 
 # the root 'shared/' remains the Single Source of Truth.
-extension/shared/
+extension/shared/*
+!extension/shared/README.md
 
 # Temporary scratch files
 scratch/

extension/shared/README.md

@@ -0,0 +1,14 @@
+# ⚠️ READ BEFORE EDITING
+
+This directory is a **MIRROR** of the root `/shared` folder.
+
+**DO NOT edit these files directly.** Any changes made here will be overwritten the next time the synchronization script is run.
+
+### Proper Workflow:
+1.  **Edit** the source files in the root `[repo_root]/shared/` directory.
+2.  **Run** the synchronization script:
+    -   **Windows**: `[repo_root]\scripts\sync-constants.bat`
+    -   **Linux/macOS**: `[repo_root]/scripts/sync-constants.sh`
+3.  **Verify** that the changes have propagated to this folder.
+
+Failure to follow this protocol will result in out-of-sync components and broken protocol logic.

shared/blacklist.js

@@ -1,6 +1,10 @@
 /**
  * blacklist.js
  * 
+ * ⚠️ WARNING: This is the SINGLE SOURCE OF TRUTH.
+ * If you edit this file, you MUST run /scripts/sync-constants.bat 
+ * to propagate changes to the extension and relay server.
+ * 
  * Domains to be filtered out from the tab selection dropdown to reduce "noise".
  * These are typically sites that won't contain shareable video content.
  */

shared/constants.js

@@ -1,5 +1,9 @@
 /**
  * KoalaSync Shared Constants & Protocol Definitions
+ * 
+ * ⚠️ WARNING: This is the SINGLE SOURCE OF TRUTH.
+ * If you edit this file, you MUST run /scripts/sync-constants.bat 
+ * to propagate changes to the extension and relay server.
  */
 
 export const PROTOCOL_VERSION = "1.0.0";