Introduce an embedded Web File Explorer (zhttpd) and unified event loop implementation. Adds HTTP server headers and sources (http_api, http_parser, http_response, http_server, http_csrf, http_config), kqueue-based event loop (event_loop + event_loop_kqueue), embedded resource tooling and web UI (index.html, app.js, style.css, tools/generate_resources.py), API docs (docs/API.md), and tests (tests/test_http_query.c). Update Makefile to add ENABLE_ZHTTPD toggle (enabled by default on PS4/PS5), visibility flag for console targets, and test target for the new HTTP query test. Minor cleanup to include/ftp_config.h formatting and add ftpd.log to .gitignore.
