Add robots meta tags on pages in robots.txt

Useful when app is at a non-root path and we're not handling top-level
/robots.txt requests.

app/templates/followers.html

@@ -3,6 +3,7 @@
 
 {% block head %}
 <title>{{ local_actor.display_name }}'s followers</title>
+<meta name="robots" content="noindex, nofollow">
 {% endblock %}
 
 {% block content %}

app/templates/following.html

@@ -3,6 +3,7 @@
 
 {% block head %}
 <title>{{ local_actor.display_name }}'s follows</title>
+<meta name="robots" content="noindex, nofollow">
 {% endblock %}
 
 {% block content %}

app/templates/login.html

@@ -1,5 +1,8 @@
 {%- import "utils.html" as utils with context -%}
 {% extends "layout.html" %}
+{% block head %}
+<meta name="robots" content="noindex, nofollow">
+{% endblock %}
 {% block main_tag %} class="main-flex"{% endblock %}
 {% block content %}
 <div class="centered">

app/templates/remote_follow.html

@@ -3,6 +3,7 @@
 
 {% block head %}
 <title>Remote follow {{ local_actor.display_name }}</title>
+<meta name="robots" content="noindex, nofollow">
 {% endblock %}
 
 {% block content %}

app/templates/remote_interact.html

@@ -3,6 +3,7 @@
 
 {% block head %}
 <title>Interact from your instance</title>
+<meta name="robots" content="noindex, nofollow">
 {% endblock %}
 
 {% block content %}