v0.35.1: performance, AGPL licensing and documentation overhaul

- Web Server reads static files inline; proxy middleware chain flattened
- About window with license summary and project links; AGPL-3.0-or-later
- Rewritten documentation: feature list, screenshots, performance guide
- Fix false spikes in per-Vhost request-rate charts

docs/SCREENSHOTS.md

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+# Screenshots
+
+A tour of the RustProxy administration panel. The panel runs on the separate administration listener (by default `http://127.0.0.1:9090`) and is available in English and Polish, with light and dark themes.
+
+## Sign-in
+
+Local administrator sign-in. The first account is created with a one-time setup token; there is no default password.
+
+![Sign-in](images/login.png)
+
+## Overview dashboard
+
+Live requests per second, bandwidth, status codes, cache hit ratio, protocol mix, system resources and backend health. Cards can be rearranged, resized, hidden and saved as presets.
+
+![Overview dashboard](images/overview.png)
+
+## Vhosts
+
+Every published domain with its listeners, backends, health, request rate and security options. The editor groups frontend, backends, balancing, security, cache and custom locations.
+
+![Vhost list](images/vhosts.png)
+
+![Vhost editor](images/vhost-editor.png)
+
+## Web Server
+
+Reusable Web Services for static sites and PHP applications, with presets, delivery options and generated filesystem permission commands.
+
+![Web Server](images/web-server.png)
+
+## Certificates
+
+Certificate inventory with expiry, covered hostnames, assigned Vhosts and managed ACME renewal.
+
+![Certificates](images/certificates.png)
+
+## Traffic
+
+Per-Vhost traffic analytics: top paths, clients, user agents, countries, methods and status codes.
+
+![Traffic analytics](images/traffic.png)
+
+## Cache
+
+HOT and COLD cache usage, hit ratio, stored objects and purge/ban tools.
+
+![Cache](images/cache.png)
+
+## Logs
+
+Live and stored request logs with filters, search syntax and record details.
+
+![Logs](images/logs.png)
+
+## Settings
+
+Listeners, TLS policy, security, logging, cache, compression, monitoring, administration and appearance.
+
+![Settings](images/settings.png)
+
+## Documentation and API
+
+The built-in Reader with all guides, and an interactive OpenAPI reference powered by Swagger UI. Both work offline and use the administrator session.
+
+![Documentation Reader](images/documentation.png)
+
+![API reference](images/api.png)
+
+## About
+
+Version, author, license summary and project links.
+
+![About](images/about.png)