Update browser session tools for new block macros and main merge

Rebase onto main to pick up record_correction tool, declarative block
macros (define_tool_block!/define_simple_tool_block!), layered cancel,
and configurable agent name.

Converts all 5 browser session blocks from manual boilerplate to the
new macro conventions. BrowserOpenBlock uses define_tool_block! (with
params_type + agent label), the rest use define_simple_tool_block!.

https://claude.ai/code/session_01QvEcr1eaxtqwA2Ry5DGwhp

Author: claude