Fixes#2180Fixes#2181
Migrate the gateway from Fiber v2 to Fiber v3.3.0 and update the affected server, middleware, handler, controller, and test code for the new APIs.
Replace the deprecated Fiber filesystem middleware used by the WebUI with the Fiber v3 static middleware, serving the embedded WebUI assets from an fs.Sub filesystem.
Fix the request header limit handling regression by adding a temporary handler for Fiber v3/fasthttp small-buffer errors so oversized request headers return the expected regulated S3 error response.
Fix the debuglogger panic by reworking the boxed key/value formatter used for debug request and response dumps. The formatter now handles long header keys and values without producing invalid wrap widths, negative padding, or out-of-range string slices.
niksis02
jonaustin09