fix(chat): suppress 'stop' badge in metadata footer for normal turn ends

Every text-bearing assistant turn finalizes with `finishReason="stop"`
(set by `RichChatViewModel.finalizeStreamingMessage` line 881 — the
standard end-of-turn signal Hermes/ACP/OpenAI all emit). The
`metadataFooter` in `RichMessageBubble` was rendering it
unconditionally, so every assistant bubble carried a `· stop · TIME`
footer. Combined with terse model output (e.g. deepseek-v4-flash
emitting only a brief status line before ending the turn), the
badge created a misleading "the agent gave up" impression — there
was no warning, error, or actual failure.

Match the convention used by ChatGPT, Claude.ai, Cursor, etc.:
suppress the badge for normal end-of-turn (`stop` / `end_turn`),
reserve it for abnormal terminations the user actually wants to
see (`max_tokens`, `length`, `error`, `refusal`, `content_filter`,
…). When it does render, color it with severity tone — warning
yellow for "response cut short" cases, danger red for failures
and refusals, muted otherwise.

The existing `handlePromptComplete` system-message-injection path
(line 725-751) for non-`end_turn` stops still surfaces those cases
explicitly at the top of the chat — this change only trims the
always-on badge from the per-message footer.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scarf/scarf/Features/Chat/Views/RichMessageBubble.swift

@@ -348,10 +348,13 @@ struct RichMessageBubble: View, Equatable {
                 Text("\(tokens) tok")
                     .font(ChatFontScale.monoSmall(chatFontScale))
             }
-            if let reason = message.finishReason, !reason.isEmpty {
+            if let reason = message.finishReason,
+               Self.shouldShowFinishReason(reason)
+            {
                 Text("·")
                 Text(reason)
                     .font(ChatFontScale.caption(chatFontScale))
+                    .foregroundStyle(Self.finishReasonTone(reason))
             }
             if let time = message.timestamp {
                 Text("·")
@@ -377,6 +380,36 @@ struct RichMessageBubble: View, Equatable {
         .padding(.leading, 4)
     }
 
+    /// Whether `finishReason` should render as a visible badge in the
+    /// message footer. `stop` and `end_turn` are normal end-of-turn
+    /// signals — `RichChatViewModel.finalizeStreamingMessage` stamps
+    /// `"stop"` on every text-bearing turn-final assistant message —
+    /// so showing them creates the impression that something stopped
+    /// the agent prematurely. We suppress them and reserve the badge
+    /// for abnormal terminations (max_tokens, error, refusal,
+    /// content_filter, …) the user actually wants to see. Matches
+    /// the conventions in ChatGPT, Claude.ai, Cursor, etc.
+    private static func shouldShowFinishReason(_ reason: String) -> Bool {
+        let normalized = reason.trimmingCharacters(in: .whitespaces).lowercased()
+        return !["stop", "end_turn", "end-turn", ""].contains(normalized)
+    }
+
+    /// Visual tone for an abnormal finish-reason badge. Severity
+    /// scales: warning (yellow) for "the response was cut short" cases
+    /// the user can usually retry, danger (red) for outright failures
+    /// or refusals, muted otherwise so unrecognized reasons stay
+    /// readable but un-alarming.
+    private static func finishReasonTone(_ reason: String) -> Color {
+        switch reason.lowercased() {
+        case "max_tokens", "length", "content_filter":
+            return ScarfColor.warning
+        case "error", "refusal":
+            return ScarfColor.danger
+        default:
+            return ScarfColor.foregroundMuted
+        }
+    }
+
     /// Speaker glyph that toggles `AVSpeechSynthesizer` playback for
     /// the assistant reply. Lives in its own view so the
     /// `MessageSpeechService` observation doesn't fight the bubble's