Outline: share as a read-only link

- Share on the Outline page opens a sheet: create / copy / turn off a
  read-only link, share the link with the system share sheet, or send the
  outline as text
- The link has its own token (separate from the whole-study share link) and
  the public endpoint returns only the outlines, rebuilt field by field:
  no observations, interpretations, applications, scripts or word notes
- Opening the link shows the outline(s) with no sign-in, a switcher between
  the whole-study and per-chunk outlines, and Print / PDF
- New outline_share_token column (added automatically on start)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/hooks/useOutlineShareLink.js

@@ -0,0 +1,44 @@
+// The read-only link to a study's outlines: status, create, turn off, copy. A separate link from the
+// whole-study share link, and it only ever shows outlines.
+import { useEffect, useState } from 'react';
+import { disableOutlineSharing, enableOutlineSharing, getOutlineShareStatus } from '../syncService.js';
+
+export function useOutlineShareLink(projectId, enabled = true) {
+  const [token, setToken] = useState(null);
+  const [state, setState] = useState('loading'); // 'loading' | 'ready' | 'unavailable' (no account / server)
+  const [busy, setBusy] = useState(false);
+  const [error, setError] = useState('');
+
+  useEffect(() => {
+    setToken(null);
+    setError('');
+    if (!projectId || !enabled) return undefined;
+    let active = true;
+    setState('loading');
+    getOutlineShareStatus(projectId).then((result) => {
+      if (!active) return;
+      if (result.ok) { setToken(result.data.shareToken); setState('ready'); } else setState('unavailable');
+    });
+    return () => { active = false; };
+  }, [projectId, enabled]);
+
+  const url = token ? `${window.location.origin}${window.location.pathname}?outline=${token}` : '';
+
+  const create = async () => {
+    setBusy(true);
+    setError('');
+    const result = await enableOutlineSharing(projectId);
+    setBusy(false);
+    if (result.ok) setToken(result.data.shareToken);
+    else setError(result.status === 404 ? 'Your study hasn’t synced to your account yet. Wait a moment and try again.' : 'Couldn’t create the link. Check your connection and try again.');
+  };
+
+  const turnOff = async () => {
+    setBusy(true);
+    const result = await disableOutlineSharing(projectId);
+    setBusy(false);
+    if (result.ok) setToken(null); else setError('Couldn’t turn the link off. Try again.');
+  };
+
+  return { token, url, state, busy, error, create, turnOff };
+}