Port 4ducky to Rust (Axum + SQLite)

Same design, layout, URLs and features as the PHP version: browse grid,
image view with AJAX comments, BBCode, likes, uploads (file, URL and
bookmarklet), quicktagger, profile, block list, inbox, invites, Hall of
Ducks, Truhe, abuse reports and the admin tools.

- Parameterized SQL, escaped templates (askama), argon2 passwords,
  server-side sessions, CSRF tokens on every write, strict script CSP
- SSRF-safe remote image fetching, magic-byte upload checks
- Self-hosted captcha replaces reCAPTCHA v1; analytics/social widgets removed
- Vanilla JS replaces jQuery and its plugins with the same DOM behaviour
- Reverse proxy support (frontend_path, trust_proxy, secure_cookies)
- Admin CLI: admin, settings, invites

See README.md for running it and the full list of changes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

templates/abuse.html

@@ -0,0 +1,13 @@
+{% include "header.html" %}
+{%- if ok %}
+			<div class="success" style="text-align:center">
+				Abused. Wait for response.<br><br>
+                <strong>{% if let Some(r) = referer %}<a href="{{ r }}">&#187; back</a>{% endif %}</strong>
+			</div>
+{%- else %}
+			<div class="warn" style="text-align:center">
+				Abused failed.<br><br>
+                 <strong>{% if let Some(r) = referer %}<a href="{{ r }}">&#187; back</a>{% endif %}</strong>
+			</div>
+{%- endif %}
+{% include "footer.html" %}