Refactor apropos/charte/licence pages: shared layout, TOC anchors, and UI polish

Unify the three public pages (à propos, charte, licence) onto a single
grid layout (.page-content) with sticky TOC sidebar, replacing the old
separate  /  /  markup.

- Merge about.php, charte.php, licence.php templates into shared
  .page-content / .content-section structure
- Add CommonMark HeadingPermalinkExtension for stable heading anchors
- Use SlugNormalizer for TOC links so they match rendered heading IDs
- Standardize link styling across content blocks: bold black, accent on
  hover (consistent with global link style)
- Fix code block wrapping: use pre-wrap instead of pre, constrain grid
  columns with min-width:0, auto scrollbar
- Fix apropos page grid placement: force content-section into column 2
  so contacts and credits stay in the content area, not the sidebar

Also includes accumulated WIP changes:
- Header gradient: hardcoded purple-to-green (replaces CSS variables)
- Search placeholder font
- Duration field: replace minutes/sec/heures with h:m:s time inputs
- TFE file optional for formats 1,4,6 with client-side JS toggle
- Licence form: em-dash to hyphen, details/summary classes
- Pill search: block Enter key form submission when no results
- Draft autosave: remove CSRF rotation (broke concurrent FilePond uploads)
- Language pill: clear hints for excluded main languages
- Search results: gradient placeholder cards for items without covers
- TFE display: format durée values as XhYm instead of decimal

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

@@ -643,6 +643,7 @@
 			enableFilepondMode();
 			_xamxamFilepondReady = false;
 			window.XamxamInitFilePonds();
+			if (window.XamxamUpdateTfeRequired) window.XamxamUpdateTfeRequired();
 			setTimeout(() => {
 				_xamxamFilepondReady = true;
 			}, 0);
@@ -694,6 +695,68 @@
 		}
 	});
 
+	// ── TFE file optional when Site web (1), Performance (4) or Installation (6) ──
+	// The format checkboxes no longer trigger HTMX swaps; this JS toggles the TFE
+	// required attribute and asterisk client-side so the student sees immediate feedback.
+	// admin_mode hidden input (value="1") suppresses required toggling for admins.
+	(function () {
+		var optionalFormatIds = ["1", "4", "6"];
+
+		function isAdminMode() {
+			var el = document.querySelector('input[name="admin_mode"]');
+			return el && el.value === "1";
+		}
+
+		function updateTfeRequired() {
+			if (isAdminMode()) return;
+
+			var tfeInput = document.getElementById("tfe-files-input");
+			if (!tfeInput) return;
+
+			var checkedAny = false;
+			var boxes = document.querySelectorAll('input[name="formats[]"]:checked');
+			for (var i = 0; i < boxes.length; i++) {
+				if (optionalFormatIds.indexOf(boxes[i].value) !== -1) {
+					checkedAny = true;
+					break;
+				}
+			}
+
+			// Find the label for the TFE input (its parent group's <label>)
+			var fieldGroup = tfeInput.closest(".admin-files-fieldgroup");
+			var label = fieldGroup ? fieldGroup.querySelector("label[for='tfe-files-input']") : null;
+
+			if (checkedAny) {
+				tfeInput.removeAttribute("required");
+				// Replace asterisk + optional text
+				if (label) {
+					label.textContent = "TFE (optionnel pour ce format)";
+				}
+			} else {
+				tfeInput.setAttribute("required", "");
+				if (label) {
+					label.innerHTML = "TFE <span class='asterisk'>*</span>";
+				}
+			}
+		}
+
+		// Delegate change events on the format fieldset
+		var formatFieldset = document.getElementById("fieldset-formats");
+		if (formatFieldset) {
+			formatFieldset.addEventListener("change", function (e) {
+				if (e.target && e.target.name === "formats[]") {
+					updateTfeRequired();
+				}
+			});
+		}
+
+		// Run once on page load
+		updateTfeRequired();
+
+		// Expose for HTMX afterSwap re-init
+		window.XamxamUpdateTfeRequired = updateTfeRequired;
+	})();
+
 	// ── Relink file browser ──────────────────────────────────────────
 
 	/**

app/public/assets/js/app/pill-search.js

@@ -159,8 +159,14 @@
 				}
 				highlight(selectedIdx);
 			} else if (e.key === "Enter") {
+				// Always prevent Enter from submitting the form.
+				// If there are no suggestions (e.g., "anglais" in language
+				// search — excluded main language), the Enter key would
+				// otherwise propagate to the form and trigger its hx-post to
+				// draft.php, causing the JSON response to replace the form
+				// content.
+				e.preventDefault();
 				if (items.length > 0) {
-					e.preventDefault();
 					if (selectedIdx >= 0 && selectedIdx < items.length) {
 						selectPill(items[selectedIdx]);
 					} else {