fix(ios): start incremental speech at soft boundaries (#33305)

Merged via squash.

Prepared head SHA: d1acf72317
Co-authored-by: mbelinky <132747814+mbelinky@users.noreply.github.com>
Co-authored-by: mbelinky <132747814+mbelinky@users.noreply.github.com>
Reviewed-by: @mbelinky

apps/ios/Tests/TalkModeIncrementalSpeechBufferTests.swift

@@ -0,0 +1,28 @@
+import Testing
+@testable import OpenClaw
+
+@MainActor
+@Suite struct TalkModeIncrementalSpeechBufferTests {
+    @Test func emitsSoftBoundaryBeforeTerminalPunctuation() {
+        let manager = TalkModeManager(allowSimulatorCapture: true)
+        manager._test_incrementalReset()
+
+        let partial =
+            "We start speaking earlier by splitting this long stream chunk at a whitespace boundary before punctuation arrives"
+        let segments = manager._test_incrementalIngest(partial, isFinal: false)
+
+        #expect(segments.count == 1)
+        #expect(segments[0].count >= 72)
+        #expect(segments[0].count < partial.count)
+    }
+
+    @Test func keepsShortChunkBufferedWithoutPunctuation() {
+        let manager = TalkModeManager(allowSimulatorCapture: true)
+        manager._test_incrementalReset()
+
+        let short = "short chunk without punctuation"
+        let segments = manager._test_incrementalIngest(short, isFinal: false)
+
+        #expect(segments.isEmpty)
+    }
+}