feat(cli): add network response subcommand for body capture

[mvanhorn]

Summary

Wire the existing responsebody daemon handler to a new CLI subcommand: network response <url-pattern>. This lets users capture response bodies from the command line, which was previously only available via batch/JSON mode.

# Wait for a matching response and print its body
agent-browser network response "/api/products"

# With custom timeout
agent-browser network response "/api/data" --timeout 10000

Closes #111

Evidence

Signal	Source
Issue #111	"network requests --body: include response bodies for scraping workflows"
PR #464	Prior attempt (too broad scope - response + dump + filters). Never merged.
Existing handler	handle_responsebody already implements CDP Network.getResponseBody but had no CLI command
Reddit r/mcp	Benchmarked API costs of AI browser agents - reducing duplicate fetch calls saves tokens
#555	network requests does not capture navigations - agents need better network introspection
Firecrawl Analysis	agent-browser listed among top 11 AI browser agents but noted CLI overhead

Implementation

The daemon's handle_responsebody handler was already complete - it subscribes to Network.responseReceived events, matches URLs, and calls Network.getResponseBody. This PR adds:

• network response subcommand in parse_network (commands.rs)
• --timeout flag support (default 30s)
• Human-readable output for response body (output.rs)
• Help text and tests

Files changed

• cli/src/commands.rs - add response to parse_network VALID list and parser
• cli/src/output.rs - response body output handler, help text updates

Test plan

• cargo fmt passes
• cargo clippy passes
• cargo test passes (476 tests, 0 failures)
• Manual: agent-browser network response "/api/*" returns matching body

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

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