The status row stops pinning on a finished command

Fixed

• The live status row no longer pins on a command that has already finished. A command that yields to a background job keeps its tool call open until the job's own completion arrives, and that completion is now reported to the row directly instead of being inferred from a stream that may never carry it. A run whose finish was dropped is treated as stale rather than busy forever, so the watchdog can still recover it.
• One block no longer retitles the row "Blocked" for the rest of the run. A block is a moment: the next step, tool call, or model response clears it.
• Two tools in one step can no longer be mistaken for each other. The local model path now gives each tool call a stable id, and the fallback key includes the tool name, so one call's finish cannot delete another's.
• The agent works in one browser tab per chat. A new task in the same chat reuses the tab that chat was already working in instead of opening another one, and sending a task while you are looking at a tab hands that tab to the agent. A tab you have taken control of is never adopted, and an agent-originated open no longer moves focus off the composer.
• A workspace that fails to load shows the error with a "Try again" button instead of an empty chat with no way back. A transient failure while preloading a chat is no longer cached as "this chat has nothing", which used to leave that pane blank for the rest of the session.
• A background run that ended in a pause shows its dot before you open the chat. A buffered finish now settles the run's status, and a stream that ends without one is settled too, so the sidebar stops pulsing for a run that is over.
• The sidebar's Running filter and the status dot now agree, so a row showing an attention dot cannot be hidden by the filter. The session cap also protects a running or needs-input session from being evicted, so a just-started run cannot lose its row.
• The take-control and annotate chrome is hidden while a clip is being recorded, so it stays out of the video. The cursor, highlight, and border stay, because they are what shows what the agent did.