browser skill: cdp() helper broken (sessionId binding) + activate_tab/list_tabs not exported to heredoc env

[rz1989s]

Repro (pi session, macOS, Chrome CDP attach, browser_harness 0.1.4):

browser-use <<'PY'
cdp("Target.activateTarget", {"targetId": "<tid>"})
PY
# RuntimeError: {'code': -32602, 'message': 'Invalid parameters', 'data': 'Failed to deserialize params.targetId - BINDINGS: mandatory field missing at position 8'}

browser-use <<'PY'
cdp("Input.insertText", {"text": "hello"})
PY
# RuntimeError: {'code': -32600, "Message may have string 'sessionId' property"}

Expected: cdp() passes params through to the attached page session; documented tab helpers from interaction-skills/tabs.md (activate_tab, list_tabs) are pre-imported alongside switch_tab/new_tab.

Actual:

1. cdp() mangles params/session binding for both Target- and Input-domain methods — unusable for keyboard events (Input.insertText / dispatchKeyEvent). Workaround used: js() native-setter + execCommand, and click_at_xy where DOM clicks failed.
2. tabs.md documents activate_tab()/list_tabs() but the heredoc env only has switch_tab (NameError: activate_tab not defined); had to fall back to raw switch_tab only, no bring-to-front.

Why it matters: coordinate/js clicks + native-setter worked, but typing into React controlled inputs required real keyboard events — the exact case cdp() exists for. Also the profile/notifications panels opened from stray click_at_xy near the top-right and there was no clean way to dismiss via CDP.

Env: browser_harness 0.1.4 (0.1.10 update available — untested there), macOS, pi heredoc mode.