feat: inline entry title renaming (#14)

* feat: inline entry title renaming

- database.rs: add update_entry_title(conn, entry_uid, title) -> Result<bool>
  targets archived_entries table; returns false for unknown uid
- routes.rs: PATCH /api/archives/:archive_id/entries/:entry_uid (ROLE_USER)
  maps false -> 404; 3 tests (401 unauthed, 204+persists, 404 unknown uid)
- api.js: updateEntryTitle(archiveId, entryUid, title)
- ContextRail.jsx: click title h2 -> inline input; Enter/blur commits,
  Escape cancels (cancel ref prevents double-save on blur after Escape);
  pencil icon fades in on hover as edit affordance
- App.jsx: handleEntryTitleChange mutates entries + selectedEntry in-place
- styles.css: rail-title--editable cursor/hover, pencil icon show/hide,
  rail-title-input underline style
- rebuild frontend bundle

* chore: remove + prefix from Capture button label

frontend/src/styles.css

@@ -1349,3 +1349,37 @@ select {
   }
   .entry-table { min-width: 860px; }
 }
+
+/* Inline title edit in ContextRail */
+.rail-title--editable {
+  cursor: pointer;
+}
+.rail-title--editable:hover {
+  opacity: 0.75;
+}
+.rail-title--editable .edit-icon {
+  display: inline-block;
+  width: 0.75em;
+  height: 0.75em;
+  margin-left: 0.35em;
+  vertical-align: middle;
+  opacity: 0;
+  transition: opacity 0.1s;
+  flex-shrink: 0;
+}
+.rail-title--editable:hover .edit-icon {
+  opacity: 0.5;
+}
+.rail-title-input {
+  width: 100%;
+  font: inherit;
+  font-size: inherit;
+  font-weight: 600;
+  background: transparent;
+  border: none;
+  border-bottom: 1px solid currentColor;
+  color: inherit;
+  padding: 0;
+  margin: 0 0 8px;
+  outline: none;
+}