feat(chat): interactive diff view for file edit and patch tool output (#738) (#741)

* feat(chat): interactive diff view for patch and file edit tool output

* fix(chat): address agy review feedback for diff viewer UX and layout

* fix(chat): suppress raw text/json when diff view renders and fix sync message ordering race (#741)

* fix(tests): resolve nullable smart-cast errors in ToolBubbleParsingTest

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Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/theme/Color.kt

@@ -98,3 +98,11 @@ val CodeTerminalBg = Color(0xFF1E1E1E)
 val CodeTerminalBorder = Color(0xFF333333)
 val CodeTerminalText = Color(0xFFD4D4D4)
 val CodeTerminalMuted = Color(0xFF808080)
+
+// ── Diff viewer tokens (issue #738) ──────────────────────────────────
+val CodeDiffAddBg = Color(0x263DDC84)
+val CodeDiffAddText = Color(0xFF3DDC84)
+val CodeDiffDeleteBg = Color(0x26FF5C5C)
+val CodeDiffDeleteText = Color(0xFFFF5C5C)
+val CodeDiffHunkBg = Color(0x264DA8FF)
+val CodeDiffHunkText = Color(0xFF4DA8FF)