Recommend dedicated modem user in setup and install guide

- INSTALL.md: Add collapsible FRITZ!Box user creation guide in the
  First-Time Setup section with step-by-step instructions
- setup.html / settings.html: Add hint text suggesting a dedicated user
- i18n.py: Add modem_user_hint translation (EN/DE)

A dedicated user with only "Access to FRITZ!Box settings" provides
credential isolation without requiring full admin access.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: itsDNNS

INSTALL.md

@@ -212,11 +212,29 @@ When you open DOCSight for the first time, a setup wizard guides you through the
 
 ### Step 1: Modem Connection
 
+> **Recommended: Create a dedicated user**
+>
+> Instead of using your main admin account, create a separate user for DOCSight on your router. This way you can rotate or revoke its credentials independently.
+>
+> <details>
+> <summary>How to create a dedicated user on a FRITZ!Box</summary>
+>
+> 1. Open `http://fritz.box` and log in as admin
+> 2. Go to **System** > **FRITZ!Box Users** > **Add User**
+> 3. Set username (e.g. `docsight`) and a password
+> 4. Enable **only** "Access to FRITZ!Box settings" - disable everything else
+> 5. Click **Apply**
+>
+> Use this new username and password in DOCSight instead of your admin credentials.
+>
+> *Note: "Access to FRITZ!Box settings" is the only permission DOCSight needs. Unfortunately, FRITZ!Box does not offer a read-only option - this is an AVM limitation. DOCSight only reads data and never modifies any settings.*
+> </details>
+
 | Field | What to enter |
 |---|---|
 | **Modem URL** | Your modem's web interface address (e.g. `http://192.168.178.1`) |
-| **Username** | Your modem login username |
-| **Password** | Your modem login password |
+| **Username** | Your dedicated DOCSight user (or admin username) |
+| **Password** | The corresponding password |
 
 Click **Test Connection** to verify DOCSight can reach your router. If successful, continue to the next step.
 

app/i18n.py

@@ -104,6 +104,7 @@
     # Setup
     "initial_setup": "Initial Setup",
     "modem_connection": "Modem Connection",
+    "modem_user_hint": "Tip: Create a dedicated user for DOCSight instead of using your main admin account.",
     "url": "URL",
     "username": "Username",
     "password": "Password",
@@ -264,6 +265,7 @@
 
     "initial_setup": "Ersteinrichtung",
     "modem_connection": "Modem-Verbindung",
+    "modem_user_hint": "Tipp: Lege einen eigenen Benutzer fuer DOCSight an, anstatt deinen Haupt-Admin zu verwenden.",
     "url": "URL",
     "username": "Benutzername",
     "password": "Passwort",

app/templates/settings.html

@@ -157,6 +157,7 @@ <h1>{{ t.settings }}</h1>
 
     <div class="section">
         <h2>{{ t.modem_connection }}</h2>
+        <p style="font-size:0.85em; color:var(--muted); margin-bottom:12px;">{{ t.modem_user_hint }}</p>
         <div class="form-grid">
             <div class="form-row full">
                 <label for="modem_url">{{ t.url }}</label>

app/templates/setup.html

@@ -200,6 +200,7 @@ <h1>DOCSight</h1>
 
     <div class="section">
         <h2><span class="step-num">1</span>{{ t.modem_connection }}</h2>
+        <p style="font-size:0.85em; color:var(--muted); margin-bottom:12px;">{{ t.modem_user_hint }}</p>
         <div class="form-grid">
             <div class="form-row full">
                 <label for="modem_url">{{ t.url }}</label>