refactor: move AGENT.md and AGENT.ko.md to .agents/ directory

deploy/install.sh

@@ -128,7 +128,7 @@ if ! check_assets_present "."; then
 
   # Copy non-dev documents if they don't already exist.
   # We skip dev-specific docs like README.md, DONE.md, and FUTURE_WORKS.md.
-  for doc in AGENT.md AGENT.ko.md MESSAGING.md BOOTSTRAP.md BOOTSTRAP.ko.md INSTRUCTION.md; do
+  for doc in MESSAGING.md BOOTSTRAP.md BOOTSTRAP.ko.md INSTRUCTION.md; do
     if [ -f "$STAGE_DIR/$doc" ] && [ ! -e "$doc" ]; then
       cp "$STAGE_DIR/$doc" . || { echo "❌ Error: Failed to copy $doc" >&2; exit 1; }
       echo "$doc" >> "$MANIFEST_FILE"