feat: add assert commands for test assertions with exit codes

[mvanhorn]

Summary

Adds an assert command family for verifying expected state in automation pipelines. Each command reuses existing daemon actions and exits with code 1 on failure.

Commands

Command	Description
assert visible @ref	Assert element is visible
assert hidden @ref	Assert element is NOT visible
assert text @ref "expected"	Assert element contains text
assert url "**/dashboard"	Assert URL matches glob pattern
assert title "Page Title"	Assert page title matches
assert enabled @ref	Assert element is enabled
assert checked @ref	Assert element is checked

Why this matters

The batch command (#865) enables multi-step workflows, but there's no way to verify expected state between steps. The is commands (commands.rs:1690) return true/false as JSON but don't fail the process. Assertions with exit codes are the missing piece for CI/CD and agent pipelines.

Every testing framework (Playwright, Cypress, Selenium) has assertion primitives. This brings the same capability to agent-browser's CLI.

Changes

• cli/src/commands.rs: New parse_assert function (follows parse_is pattern). Sends same daemon actions with assert: true metadata. Unit tests included.
• cli/src/main.rs: Assert evaluator intercepts responses before normal output. Prints PASS/FAIL. Glob matcher for URL patterns (* = non-slash, ** = any chars). Exits 1 on failure. Works in batch mode with --bail.
• cli/src/output.rs: Help text for assert commands.

No new daemon code - reuses isvisible, isenabled, ischecked, gettext, url, and title actions.

Usage

agent-browser open https://example.com/login
agent-browser type @username "admin"
agent-browser click @submit
agent-browser assert url "**/dashboard"
agent-browser assert visible @welcome-banner
agent-browser assert text @greeting "Welcome"

Testing

• cargo check passes
• Unit tests for all parse_assert subcommands
• Glob matcher tested for * and ** patterns

This contribution was developed with AI assistance (Claude Code).

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[vercel]

In single-command mode with --json, a passing assert falls through without printing structured JSON output, instead printing the raw daemon response.