feat(mcp): let the connector address carry its own key

verdande could not be added to Claude at all. The documented setup —
POST /api/v1/mcp with an Authorization header — cannot be configured from
Claude's custom-connector dialog, which asks for a name, a URL and OAuth
client credentials and has no field for a bearer token. The instructions
described something the interface does not offer.

Worse, the obvious guess failed silently in the most misleading way
available: /mcp was not a route, so the SPA fallback answered 200 with a
page of HTML. The connector reported a successful connection and then
failed to parse the response, which reads as a broken client rather than
a missing endpoint.

So /mcp exists now and takes its credential in the query string, exactly
as the calendar feed does and for the same reason: a client that cannot
be told to send a header means the address is the credential. The
request logger records paths without their query strings, so the key does
not reach the log.

It is deliberately outside /api/v1 and accepts the key and nothing else.
Reading a session cookie here would make it a state-changing POST outside
the CSRF check — a cross-site request that acts as whoever is signed in —
and there is a test that fails if that ever becomes true.

The API path is unchanged for anything that can send a header. The tokens
page now shows the connector address next to the token it belongs to,
since that is the one moment the token exists.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

web/src/routes/indstillinger/tokens/+page.svelte

@@ -20,6 +20,10 @@
 	/** The plaintext of the token just minted. Held only in this variable. */
 	let fresh = $state(null);
 	let copied = $state(false);
+	let connectorCopied = $state(false);
+
+	/** What Claude's connector dialog needs, which is a URL and nothing else. */
+	let connectorURL = $derived(fresh ? `${location.origin}/mcp?key=${fresh.token}` : '');
 
 	$effect(() => {
 		api
@@ -59,6 +63,15 @@
 		}
 	}
 
+	async function copyConnector() {
+		try {
+			await navigator.clipboard.writeText(connectorURL);
+			connectorCopied = true;
+		} catch {
+			app.toast('Kunne ikke kopiere — markér teksten i stedet.');
+		}
+	}
+
 	async function revoke(token) {
 		if (!confirm(`Tilbagekald "${token.name}"? Alt, der bruger den, holder op med at virke.`))
 			return;
@@ -100,6 +113,22 @@
 				{#if copied}<span class="saved">Kopieret.</span>{/if}
 				<button class="secondary" onclick={() => (fresh = null)}>Færdig</button>
 			</div>
+
+			<!-- Shown here and nowhere else, because it contains the token, and the
+			     token exists only in this moment. Claude's connector dialog takes a
+			     URL and nothing else — there is no field for a header — so this is
+			     the form it has to be in. -->
+			<div class="also">
+				<p class="hint">
+					Skal du bruge den som <a href="/indstillinger/integrationer">MCP-forbindelse</a>
+					i Claude? Så er det denne adresse, dialogen skal have:
+				</p>
+				<p class="mono value">{connectorURL}</p>
+				<div class="row">
+					<button class="secondary" onclick={copyConnector}>Kopiér adressen</button>
+					{#if connectorCopied}<span class="saved">Kopieret.</span>{/if}
+				</div>
+			</div>
 		</div>
 	{/if}
 
@@ -194,6 +223,18 @@
 		user-select: all;
 	}
 
+	.also {
+		display: flex;
+		flex-direction: column;
+		gap: var(--s2);
+		padding-top: var(--s3);
+		border-top: 1px solid var(--accent);
+	}
+
+	.also a {
+		color: inherit;
+	}
+
 	.what {
 		display: flex;
 		flex-direction: column;