chore: add docker infrastructure, gists feature, attachment system, and admin CLI tools

- Add .dockerignore, Dockerfile, and docker compose targets to Makefile for containerized deployment
- Implement gists router with CRUD operations, database schema, and polymorphic comment/vote reuse
- Create attachment upload system with thumbnail generation, MIME detection, and storage path management
- Add attachments_prune CLI command to clean orphaned attachment records and files
- Introduce rate limiting middleware with 60 requests per minute window
- Add custom 404 and 500 error handlers with SEO-optimized template responses
- Extend database initialization with gists and attachments indexes plus upload site settings defaults
- Update load_comments to include attachment mapping for comment resources
- Register gists and uploads routers in main application and update AGENTS.md documentation

devplacepy/templates/landing.html

@@ -9,7 +9,7 @@
     <section class="landing-hero">
         <h1>Devplace.net &mdash; The Developer <span>Social Network</span></h1>
         <p>Track industry shifts. Discover bold releases. Share what you're building in an open, uncensored environment.</p>
-        <a href="/auth/signup" class="landing-cta">Join DevPlace Free</a>
+        <a href="/auth/signup" class="landing-cta"><span class="icon">&#x2728;</span>Join DevPlace Free</a>
 
         <div class="landing-features">
             <div class="landing-feature">
@@ -83,7 +83,7 @@
             <article class="news-card">
                 {% if item.image_url %}
                 <div class="news-card-image">
-                    <img src="{{ item.image_url }}" alt="" loading="lazy" onerror="this.parentElement.style.display='none'">
+                    <img src="{{ item.image_url }}" alt="" loading="lazy" class="image-fallback">
                 </div>
                 {% endif %}
                 <div class="news-card-body">
@@ -117,12 +117,12 @@
     <footer class="landing-footer">
         <p>&copy; DevPlace &mdash; The Developer Social Network</p>
         <div class="landing-footer-links">
-            <a href="/feed">Posts</a>
-            <a href="/news">News</a>
-            <a href="/projects">Projects</a>
-            <a href="/auth/login">Login</a>
-            <a href="/auth/signup">Sign Up</a>
-            <a href="/bugs">Bug Report</a>
+            <a href="/feed"><span class="icon">&#x1F4DD;</span>Posts</a>
+            <a href="/news"><span class="icon">&#x1F4F0;</span>News</a>
+            <a href="/projects"><span class="icon">&#x1F680;</span>Projects</a>
+            <a href="/auth/login"><span class="icon">&#x1F511;</span>Login</a>
+            <a href="/auth/signup"><span class="icon">&#x2728;</span>Sign Up</a>
+            <a href="/bugs"><span class="icon">&#x1F41B;</span>Bug Report</a>
         </div>
     </footer>
 </div>