feat(chrome): connect CLI to the managed browser MCP

[graseeel]

Why

Verboo desktop already installs and owns the signed local verboo-in-chrome helper, Native Messaging manifest, and managed user MCP entry. The CLI could reach that entry through generic MCP support, but its inherited first-class Chrome path still expected the unrelated Anthropic host and a claude.ai subscription.

This PR links the CLI to the managed Verboo contract without creating a second installer or copying CLI credentials into the extension.

What changes

• recognizes only the desktop-managed verboo-in-chrome stdio contract
• auto-enables the managed MCP and injects browser safety/background-tab guidance
• makes --chrome require the integration and --no-chrome disable it for one process
• keeps the inherited Anthropic native host out of Verboo mode
• adds a bundled verboo-in-chrome skill for the eight real extension tools
• makes /chrome available to Verboo users and reports managed setup/connection state
• documents the macOS, Windows, and Linux setup boundary

The desktop app remains the sole owner of helper installation, upgrades, and removal. The CLI remains the MCP client.

Verification

• bun run test:isolated — 303 test files checked, no new regressions
• focused Chrome/MCP tests — 12 passed
• bun run smoke — build and 0.15.12 (Verboo Code) passed
• bun run security:pr-scan -- --base upstream/main — no suspicious additions
• live mcp doctor verboo-in-chrome — connected in 29 ms
• live MCP listTools — click, navigate, read_page, screenshot, structured_extract, tab_group, tabs, type

App-side installer and helper: graseeel/verboo_app#67

No package version bump or release is included.