Prevent duplicate approve reviews + redesign bottom bar; bump to 2.9

- Approve: rapid taps fired multiple submitReview calls that each appended a
  review, stacking duplicate entries. Add a busy guard (skip while one is in
  flight) and dedupe reviews per user so the latest replaces earlier ones;
  disable the review menu while submitting.
- Bottom bar: replace the full-width bar with a floating frosted-glass pill
  inset from the edges (like SideStore), with a highlighted capsule behind
  the active tab. Bump to 2.9.

GiteaPR/Detail/PRDetailViewModel.swift

@@ -113,12 +113,20 @@ final class PRDetailViewModel: ObservableObject {
 
     func submitReview(state: String, comment: String?) async {
         guard let client = SettingsStore.shared.client() else { return }
+        // Guard against concurrent submissions: rapid taps on Approve used to
+        // fire several requests that each appended a review, stacking
+        // duplicate entries. Skip if one is already in flight.
+        guard busyMessage == nil else { return }
         busyMessage = "Submitting…"
         defer { busyMessage = nil }
         do {
             let r = try await client.submitReview(owner: owner, repo: repo.name,
                                                   number: prNumber, state: state,
                                                   comment: comment)
+            // A user's latest review replaces their earlier ones (Gitea stores
+            // one review per user per PR). Drop any prior review by this user
+            // so we don't render duplicates.
+            reviews.removeAll { $0.user?.login == r.user?.login }
             reviews.append(r)
         } catch {
             errorMessage = error.localizedDescription