fix: repair form submission with queued files + add comprehensive debug logging

- Replace fetch(redirect:manual) with XMLHttpRequest in file-upload-queue.js.
  The previous fetch-based redirect detection was broken because opaque
  redirects hide the Location header. XHR's responseURL reliably exposes
  the final URL after server-side redirects.

- Add console.log tracing at every decision point in submit interception:
  entry, hasFiles check, enctype check, double-submit guard, XHR status,
  redirect detection, error fallback.

- Add error_log entry-point logging to all 16 admin action files plus
  the partage/index.php submission handler and password gate. Each logs:
  request method, content type/length, POST keys, file counts, and
  queue-specific file counts where applicable.

- Add double-submit guard (_xamxamActiveSubmit) to prevent duplicate
  XHR sends when the native submit handler fires after interception.

app/public/assets/js/file-upload-queue.js

@@ -363,6 +363,9 @@
 
 	// ── Form submit interception ───────────────────────────────────────────
 
+	// Track whether we've already intercepted this submit to prevent double-submit
+	var _xamxamActiveSubmit = false;
+
 	function bindFormSubmit() {
 		document.querySelectorAll("form[data-beforeunload-guard]").forEach(function (form) {
 			if (form.dataset.xamxamFormBound) return;
@@ -370,10 +373,29 @@
 
 			form.addEventListener("submit", function (e) {
 				var hasFiles = QUEUE_TYPES.some(function (qt) { return queues[qt].length > 0; });
-				if (!hasFiles) return; // Normal submit
+
+				console.log("[file-upload-queue] submit event fired | action=" + (form.getAttribute("action") || "") + " | hasFiles=" + hasFiles + " | enctype=" + form.enctype);
+
+				if (!hasFiles) {
+					console.log("[file-upload-queue] no queued files, passing through native submit");
+					markClean();
+					return; // Normal submit
+				}
 
 				// Check if the form can accept multipart
-				if (form.enctype !== "multipart/form-data") return;
+				if (form.enctype !== "multipart/form-data") {
+					console.log("[file-upload-queue] form enctype is not multipart/form-data, passing through");
+					markClean();
+					return;
+				}
+
+				// Prevent double-submit (in case native submit falls through)
+				if (_xamxamActiveSubmit) {
+					console.log("[file-upload-queue] already submitting, skipping");
+					e.preventDefault();
+					return;
+				}
+				_xamxamActiveSubmit = true;
 
 				e.preventDefault();
 
@@ -392,32 +414,53 @@
 
 				markClean();
 
-				// Use fetch so we can inspect the response before navigation.
-				// The server either redirects (302 → we navigate to that URL)
-				// or returns the form page with errors (200 → replace the page).
-				fetch(form.getAttribute("action") || "", {
-					method: "POST",
-					body: fd,
-					redirect: "manual",
-				}).then(function (resp) {
-					if (resp.type === "opaqueredirect" || resp.status === 302 || resp.status === 301) {
-						// Browser redirect — navigate the whole page
-						window.location.href = resp.headers.get("Location") || form.getAttribute("action");
+				console.log("[file-upload-queue] injecting " + QUEUE_TYPES.map(function(qt) { return qt + ":" + queues[qt].length; }).join(", ") + " files into FormData");
+
+				// Use XMLHttpRequest instead of fetch so we can reliably read the
+				// final URL after redirects (fetch with redirect:manual hides headers).
+				var xhr = new XMLHttpRequest();
+				xhr.open("POST", form.getAttribute("action") || "", true);
+				xhr.responseType = "text";
+
+				xhr.onload = function () {
+					_xamxamActiveSubmit = false;
+					var finalUrl = xhr.responseURL || "";
+
+					console.log("[file-upload-queue] XHR status=" + xhr.status + " | finalUrl=" + finalUrl + " | responseLength=" + (xhr.responseText ? xhr.responseText.length : 0));
+
+					// If the server redirected us (responseURL differs from action), navigate there.
+					// This handles the 302 redirect pattern used by formulaire.php and edit.php.
+					var actionUrl = form.getAttribute("action") || "";
+					if (finalUrl && finalUrl !== actionUrl && finalUrl !== window.location.href) {
+						console.log("[file-upload-queue] redirecting to " + finalUrl);
+						window.location.href = finalUrl;
 						return;
 					}
-					// Success or error — render the HTML response
-					return resp.text();
-				}).then(function (html) {
-					if (!html) return;
-					document.open();
-					document.write(html);
-					document.close();
-					// Re-bind after DOM replacement (for error re-renders)
-					setTimeout(window.XamxamInitFileUploads, 0);
-				}).catch(function () {
-					// Network error — fall back to native submit
+
+					// 200 with HTML — likely form errors, replace page
+					if (xhr.status >= 200 && xhr.status < 300 && xhr.responseText) {
+						console.log("[file-upload-queue] rendering error response HTML");
+						document.open();
+						document.write(xhr.responseText);
+						document.close();
+						// Re-bind after DOM replacement (for error re-renders)
+						setTimeout(window.XamxamInitFileUploads, 0);
+						return;
+					}
+
+					// Fallback: reload current page
+					console.log("[file-upload-queue] unexpected response, reloading page");
+					window.location.reload();
+				};
+
+				xhr.onerror = function () {
+					_xamxamActiveSubmit = false;
+					console.error("[file-upload-queue] XHR network error, falling back to native submit");
+					// Fall back to native submit
 					form.submit();
-				});
+				};
+
+				xhr.send(fd);
 			});
 		});
 	}