fix: stop Enter on Cancel from confirming ConfirmDialog (WCAG 3.2.2) (#27491)

On latest `dev`, `ConfirmDialog` registers `handleKeyDown` on `window` and treats **every** Enter keypress as Confirm, calling `event.preventDefault()` first so the focused control never gets its native activation.

The dialog also activates a focus trap with no `initialFocus`, so focus-trap falls back to the first tabbable node, which is the **Cancel** button. So the dialog opens with Cancel focused, and pressing Enter runs Confirm.

This is the confirm surface for Delete chat, Delete folder, Delete model, Delete knowledge base and ~40 other call sites. A keyboard user who tabs to Cancel and presses Enter deletes the thing they were trying to keep. Screen reader users are hit hardest, since they cannot see which button they are on and the control that means "back out safely" performs the irreversible action instead.

Two related paths have the same cause: Enter in the `input=true` textarea submits instead of inserting a newline, and a markdown link inside `message` (reachable via `eventConfirmationMessage` from tool `__event_call__` payloads, and via `web_search_confirmation_content`) becomes the first tabbable node, so Enter on that link confirms instead of following it.

Breaks WCAG 3.2.2 On Input (Level A): changing the focused control changes what the Enter key does, and activating a control performs a different action than the one it is labelled with. Also 2.1.1 Keyboard (Level A), since Cancel has no working keyboard activation.

Fix: let the focused control act on Enter itself, and only fall back to Confirm otherwise. Uses the same `target instanceof Element && target.closest(...)` guard already used in `Functions.svelte`, `Knowledge.svelte`, `Models.svelte`, `Prompts.svelte`, `Skills.svelte` and `Tools.svelte`. `select` is deliberately not in the list, because a native `select` does not act on Enter and excluding it would silently break confirm for the `inputType === 'select'` variant. Two stray `console.log` calls in the same function are removed.

Behaviour after this change: Enter on Cancel cancels, Enter on Confirm confirms, Enter in the textarea inserts a newline, Enter on a link follows it, and Enter anywhere else still confirms as before.

Severity: Critical. Silent, unrecoverable data loss triggered by the most ordinary keyboard interaction there is.

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src/lib/components/common/ConfirmDialog.svelte

@@ -46,12 +46,16 @@
 
 	const handleKeyDown = (event: KeyboardEvent) => {
 		if (event.key === 'Escape') {
-			console.log('Escape');
 			cancelHandler();
 		}
 
 		if (event.key === 'Enter') {
-			console.log('Enter');
+			// let the focused control act on Enter itself
+			const target = event.target;
+			if (target instanceof Element && target.closest('a, button, textarea')) {
+				return;
+			}
+
 			event.preventDefault();
 			event.stopPropagation();
 			confirmHandler();