v0.5.3

• The "thinking" spinner next to the assistant header now actually animates while a turn is streaming, instead of sitting frozen.
• Turn errors are shown as a single plain red line with no icon: a short reason plus a hint, classified for the common cases (invalid API key, rate limited, quota exhausted, access denied, server error). Example: "opencode-zen: invalid API key (401) - update this account's key in Settings > Accounts".