v0.32.2

The tab cap holds on a busy machine

Agents are held to 8 tabs; older ones are closed as new ones open. Reported: 107 agent tabs
open at once, until the browser connection and then the raw-CDP fallback stopped answering.
Two holes:

• The cap only counted tabs that answered "are you one of ours?" within 600 ms. On a heavily
  loaded machine none answered, so it counted none and closed none. Tabs the engine opened
  itself are now counted from its own record, whether or not they answer.
• The raw-CDP fallback opens tabs too, and had no cap at all. It now keeps the same record
  and the same limit. Tabs you opened yourself are never counted or closed, on either path.

wb shot says why there is no screenshot

When a capture failed, the engine reported the reason, and wb shot threw it away and
printed only "Screenshot is empty". It now prints the reason (for example a timeout). The
MCP browser_screenshot tool passes it on too.

Restarting the engine no longer erases its log

wb up truncated the engine log at every start, so the restart that follows a failure
destroyed the record of that failure. The log is now appended to, with a line marking each
start, and rotated once at 5 MB.