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

crates/archivr-core/src/database.rs

@@ -752,6 +752,16 @@ pub fn update_user_display_name(conn: &Connection, user_id: i64, display_name: O
     Ok(())
 }
 
+/// Updates the user-visible title of an archived entry.
+/// Returns `Ok(true)` if a row was updated, `Ok(false)` if the entry_uid was not found.
+pub fn update_entry_title(conn: &Connection, entry_uid: &str, title: Option<&str>) -> Result<bool> {
+    let n = conn.execute(
+        "UPDATE archived_entries SET title = ?1 WHERE entry_uid = ?2",
+        params![title, entry_uid],
+    )?;
+    Ok(n > 0)
+}
+
 pub fn get_user_display_name(conn: &Connection, user_id: i64) -> Result<Option<String>> {
     conn.query_row(
         "SELECT display_name FROM users WHERE id = ?1",