feat: add reactions, bookmarks, polls modules with session remember config

Add three new feature modules (reactions, bookmarks, polls) with corresponding database tables, indexes, and router registrations. Introduce `SESSION_MAX_AGE_REMEMBER` config for extended session duration, add `get_unread_messages` template global, and include operational defaults for rate limiting and session settings in `site_settings`.

devplacepy/static/css/landing.css

@@ -90,7 +90,6 @@
     background: var(--accent);
     color: #fff;
     font-weight: 700;
-    transition: all 0.2s;
 }
 
 .landing-cta:hover {
@@ -164,7 +163,6 @@
     font-size: 0.875rem;
     font-weight: 600;
     color: var(--accent);
-    transition: color 0.2s;
 }
 
 .landing-section-link:hover {
@@ -185,7 +183,6 @@
     display: flex;
     flex-direction: column;
     gap: 0.625rem;
-    transition: transform 0.2s, box-shadow 0.2s;
 }
 
 .landing-post-card:hover {
@@ -226,7 +223,6 @@
 
 .landing-post-title a {
     color: var(--text-primary);
-    transition: color 0.2s;
 }
 
 .landing-post-title a:hover {
@@ -264,7 +260,6 @@
     font-weight: 600;
     color: var(--accent);
     margin-left: auto;
-    transition: color 0.2s;
 }
 
 .landing-post-open:hover {