Wiki Phase 4: full-text search + revision history

Final phase of the wiki upgrade (see WIKI_UPGRADE.md).

Schema (additive): wiki_revisions table (per-save content snapshots).
The FULLTEXT index on wiki_pages(title, body) shipped in Phase 1.

Search:
- MATCH ... AGAINST natural-language search over title + body, ordered by
  relevance
- public: GET /public/wiki?q= (published only); admin: GET /admin/wiki?q=
  (all statuses)
- public wiki index gains a search box; admin list gains a search field

Revision history:
- every create/update snapshots the page into wiki_revisions
- admin endpoints: list revisions, get one, and restore (restore overwrites
  the page, rebuilds links, and appends a new revision — history stays
  append-only); logged as wiki.revision.restore
- editor gains a History modal: revision list + word-level diff (jsdiff) of a
  chosen revision against the current page, with one-click restore

Verified end-to-end: search matches body and title; two edits produce three
revisions; diff renders added/removed words; restore reverts and records a new
revision. No console errors.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/src/routes/admin/views/WikiHistory.jsx

@@ -0,0 +1,139 @@
+import { useEffect, useMemo, useState } from 'react'
+import { diffWords } from 'diff'
+import Modal from '../../../components/Modal.jsx'
+import { dateTime } from '../../../lib/format.js'
+import { api } from '../../../api/client.js'
+
+// Plain-text view of a body, for a readable word-level diff.
+function toText(html) {
+  if (!html) return ''
+  if (typeof window === 'undefined' || !window.DOMParser) return html
+  const doc = new DOMParser().parseFromString(html, 'text/html')
+  return doc.body.textContent || ''
+}
+
+export default function WikiHistory({ slug, onClose, onRestored }) {
+  const [revisions, setRevisions] = useState([])
+  const [current, setCurrent] = useState(null)
+  const [selected, setSelected] = useState(null) // full revision snapshot
+  const [loading, setLoading] = useState(true)
+  const [busy, setBusy] = useState(false)
+  const [error, setError] = useState('')
+
+  useEffect(() => {
+    let active = true
+    Promise.all([api.admin.listWikiRevisions(slug), api.admin.getWiki(slug)])
+      .then(([revs, page]) => {
+        if (!active) return
+        setRevisions(revs)
+        setCurrent(page)
+      })
+      .catch(() => active && setError('Could not load history.'))
+      .finally(() => active && setLoading(false))
+    return () => {
+      active = false
+    }
+  }, [slug])
+
+  async function selectRevision(id) {
+    setError('')
+    try {
+      const rev = await api.admin.getWikiRevision(slug, id)
+      setSelected(rev)
+    } catch (err) {
+      setError(err.message || 'Could not load revision.')
+    }
+  }
+
+  async function restore() {
+    if (!selected) return
+    if (!confirm(`Restore the page to revision #${selected.id}? This creates a new revision.`)) return
+    setBusy(true)
+    try {
+      await api.admin.restoreWikiRevision(slug, selected.id)
+      onRestored()
+    } catch (err) {
+      setError(err.message || 'Could not restore.')
+      setBusy(false)
+    }
+  }
+
+  // Diff the selected revision (old) against the current saved page (new).
+  const parts = useMemo(
+    () => (selected ? diffWords(toText(selected.body), toText(current?.body || '')) : []),
+    [selected, current],
+  )
+
+  return (
+    <Modal
+      title={`History — ${slug}`}
+      onClose={onClose}
+      width={760}
+      footer={
+        <>
+          <button onClick={onClose} disabled={busy} className="pill">
+            Close
+          </button>
+          <button onClick={restore} disabled={busy || !selected} className="btn btn-primary btn-sq">
+            {busy ? 'Restoring…' : 'Restore this revision'}
+          </button>
+        </>
+      }
+    >
+      {loading ? (
+        <span className="spin" />
+      ) : error ? (
+        <p className="sans" style={{ margin: 0, color: '#d98b84', fontSize: '0.85rem' }}>{error}</p>
+      ) : (
+        <div className="wiki-history">
+          <ul className="wiki-history-list">
+            {revisions.map((r, i) => (
+              <li key={r.id}>
+                <button
+                  type="button"
+                  className={`wiki-rev${selected?.id === r.id ? ' is-active' : ''}`}
+                  onClick={() => selectRevision(r.id)}
+                >
+                  <span className="wiki-rev-note">
+                    {r.change_note || 'Edit'}
+                    {i === 0 && <span className="wiki-rev-latest"> · latest</span>}
+                  </span>
+                  <span className="wiki-rev-meta">
+                    {dateTime(r.created_at)}
+                    {r.editor ? ` · ${r.editor}` : ''}
+                  </span>
+                </button>
+              </li>
+            ))}
+            {revisions.length === 0 && <li className="dim sans" style={{ fontSize: '0.85rem' }}>No revisions yet.</li>}
+          </ul>
+
+          <div className="wiki-history-diff">
+            {!selected ? (
+              <p className="muted sans" style={{ fontSize: '0.9rem' }}>
+                Select a revision to see what changed between it and the current page.
+              </p>
+            ) : (
+              <>
+                <p className="sans dim" style={{ margin: '0 0 10px', fontSize: '0.76rem' }}>
+                  Diff: revision #{selected.id} → current
+                </p>
+                <div className="wiki-diff">
+                  {parts.length === 0 || (parts.length === 1 && !parts[0].added && !parts[0].removed) ? (
+                    <span className="muted">No textual differences.</span>
+                  ) : (
+                    parts.map((p, i) => (
+                      <span key={i} className={p.added ? 'diff-add' : p.removed ? 'diff-del' : ''}>
+                        {p.value}
+                      </span>
+                    ))
+                  )}
+                </div>
+              </>
+            )}
+          </div>
+        </div>
+      )}
+    </Modal>
+  )
+}