docs: fix 6 documentation issues (#303, #245, #186, #134, #61, #73) (#486)

* docs: fix 6 documentation issues (#303, #245, #186, #134, #61, #73)

Addresses six open documentation issues in a single pass:

- **#303** -- Add `npx agent-browser` usage across README, SKILL.md, docs site, and `--help` output for zero-install experience. Global install is recommended as the fastest path (native Rust CLI vs Node.js indirection with npx).
- **#245** -- Document Claude Code skill installation with `npx skills add vercel-labs/agent-browser`
- **#186** -- Split installation instructions into Global (recommended), Quick Start (npx), and Project (local dependency) sections with clear guidance on when to use each
- **#134** -- Add "Why agent-browser over playwright-mcp?" comparison table to README covering output format, element selection, protocol, sessions, performance, mobile, cloud, and streaming
- **#61** -- Add "Timeouts and Slow Pages" section to SKILL.md documenting the 60s default timeout, all `wait` variants, and guidance for slow websites
- **#73** -- Replace stale `cp node_modules/...` advice with `npx skills add`, add warning against copying SKILL.md manually, add "Session Management and Cleanup" section to SKILL.md

* remove section

* fix doc

cli/src/output.rs

@@ -1888,6 +1888,13 @@ Environment:
   AGENT_BROWSER_IOS_DEVICE       Default iOS device name
   AGENT_BROWSER_IOS_UDID         Default iOS device UDID
 
+Install (recommended, fastest - native Rust CLI):
+  npm install -g agent-browser
+  agent-browser install                  # Download Chromium (first time)
+
+Try without installing (slower, routes through Node.js):
+  npx agent-browser open example.com
+
 Examples:
   agent-browser open example.com
   agent-browser snapshot -i              # Interactive elements only
@@ -1896,6 +1903,7 @@ Examples:
   agent-browser find role button click --name Submit
   agent-browser get text @e1
   agent-browser screenshot --full
+  agent-browser wait --load networkidle  # Wait for slow pages to load
   agent-browser --cdp 9222 snapshot      # Connect via CDP port
   agent-browser --auto-connect snapshot  # Auto-discover running Chrome
   agent-browser --profile ~/.myapp open example.com    # Persistent profile