fix: address santa-loop review findings (round 1)

Update remaining old-name references in body text:
- ARCHITECTURE.md:219 directory layout: languard-server-manager/ → languard-servers-manager/
- IMPLEMENTATION_PLAN.md:405 setup instructions: cd languard-server-manager → cd languard-servers-manager

ARCHITECTURE.md

@@ -1,4 +1,4 @@
-# Languard Server Manager — System Architecture
+# Languard Servers Manager — System Architecture
 
 ## Overview
 
@@ -216,7 +216,7 @@ LANGUARD_LOG_RETENTION_DAYS=7
 ## Directory Layout
 
 ```
-languard-server-manager/
+languard-servers-manager/
 ├── backend/
 │   ├── main.py                    # FastAPI app factory
 │   ├── config.py                  # Settings from env

IMPLEMENTATION_PLAN.md

@@ -1,4 +1,4 @@
-# Languard Server Manager — Implementation Plan
+# Languard Servers Manager — Implementation Plan
 
 ## Prerequisites
 
@@ -402,7 +402,7 @@ Verify React app can:
 ```bash
 # 1. Clone repo
 git clone <repo>
-cd languard-server-manager
+cd languard-servers-manager
 
 # 2. Backend
 cd backend