feat: tag delete, rename, and per-user humanize-tags display setting (#16)

* feat: add tag delete and rename (backend + frontend)

- DELETE /api/archives/:id/tags/:tag_uid — deletes tag subtree via
  recursive CTE; entry_tag_assignments cascade automatically
- PATCH  /api/archives/:id/tags/:tag_uid { name } — renames a tag
  segment (case-preserving slug), cascades full_path to all descendants
  in one transaction using hierarchy CTE (not LIKE), returns updated Tag
- database: rename_tag + delete_tag with 7 unit tests covering subtree
  cascade, collision detection, descendant path rewrite, slug stripping
- TagsView: inline rename (pencil icon / double-click → input), × delete
  with confirmation dialog (warns about child tags)
- App.jsx: handleTagRenamed rewrites tagFilter for exact + descendant
  paths; handleTagDeleted clears filter for deleted subtree
- api.js: renameTag (PATCH, returns Tag) + deleteTag (DELETE)
- ContextRail: tag pills show displayPath(full_path) (humanized) with
  raw full_path in title tooltip; humanize-tags setting coming next

* feat: per-user humanize-tags display setting

- auth DB: idempotent migration adds users.humanize_slugs INTEGER DEFAULT 0
- GET /api/auth/me: returns humanize_slugs bool
- PATCH /api/auth/me: accepts { humanize_slugs: bool }, persisted via
  database::update_user_humanize_slugs
- displayPath() helper moved to utils.js (was local to ContextRail)
- TagsView: node label shows tag.name vs tag.slug based on humanizeTags
- ContextRail: pill label applies displayPath conditionally
- App.jsx: derives humanizeTags from currentUser.humanize_slugs, passes
  to TagsView + ContextRail; filter badge label humanized when on
- Settings > Profile: Display Preferences section with checkbox toggle,
  updates backend and currentUser immediately via setCurrentUser
- api.js: patchMe(patch) for generic PATCH /api/auth/me
- Tests: auth_me default=false, PATCH persists=true (2 route tests)

frontend/src/App.jsx

@@ -12,6 +12,7 @@ import TagsView from './components/TagsView'
 import CollectionsView from './components/CollectionsView'
 import SettingsView from './components/SettingsView'
 import ContextRail from './components/ContextRail'
+import { displayPath } from './utils'
 
 export const AuthContext = createContext(null);
 
@@ -81,6 +82,8 @@ export default function App() {
     return saved === 'true'
   })
 
+  const humanizeTags = currentUser?.humanize_slugs ?? false;
+
   // Persist captureDialogOpen to sessionStorage
   useEffect(() => {
     sessionStorage.setItem('captureDialogOpen', captureDialogOpen)
@@ -186,6 +189,20 @@ export default function App() {
     if (archiveId) fetchTags(archiveId).then(setTagNodes)
   }, [archiveId])
 
+  const handleTagRenamed = useCallback((oldFullPath, newFullPath) => {
+    if (tagFilter === oldFullPath) {
+      setTagFilter(newFullPath);
+    } else if (tagFilter?.startsWith(oldFullPath + '/')) {
+      setTagFilter(newFullPath + tagFilter.slice(oldFullPath.length));
+    }
+  }, [tagFilter]);
+
+  const handleTagDeleted = useCallback((deletedFullPath) => {
+    if (tagFilter === deletedFullPath || tagFilter?.startsWith(deletedFullPath + '/')) {
+      setTagFilter(null);
+    }
+  }, [tagFilter]);
+
   const handleEntryTitleChange = useCallback((entryUid, newTitle) => {
     setEntries(prev => prev.map(e =>
       e.entry_uid === entryUid ? { ...e, title: newTitle } : e
@@ -251,7 +268,7 @@ export default function App() {
                   {resultCount && <><b>{resultCount.split(' ')[0]}</b>{' '}{resultCount.split(' ').slice(1).join(' ')}</>}
                   {tagFilter && (
                     <button className="tag-filter-badge" onClick={handleClearTagFilter}>
-                      × {tagFilter}
+                      × {humanizeTags ? displayPath(tagFilter) : tagFilter}
                     </button>
                   )}
                 </span>
@@ -275,10 +292,15 @@ export default function App() {
             {view === 'admin' && <AdminView archives={archives} />}
             {view === 'tags' && (
               <TagsView
+                archiveId={archiveId}
                 tagNodes={tagNodes}
                 tagFilter={tagFilter}
                 onTagFilterSet={handleTagFilterSet}
                 onViewChange={handleViewChange}
+                onTagRenamed={handleTagRenamed}
+                onTagDeleted={handleTagDeleted}
+                onTagsRefresh={handleTagsRefresh}
+                humanizeTags={humanizeTags}
               />
             )}
             {view === 'collections' && (
@@ -295,6 +317,7 @@ export default function App() {
             tagNodes={tagNodes}
             onTagsRefresh={handleTagsRefresh}
             onEntryTitleChange={handleEntryTitleChange}
+            humanizeTags={humanizeTags}
           />
         </main>
         <CaptureDialog