Add mouse and keyboard input abilities to web commands

[copilot-developer-agent-robch]

Added mouse and keyboard input functionality to the mdx web commands. Key changes:

• Created WebInputHelper class using Playwright API to handle input actions:

  • Mouse: click, move, drag/drop, scroll
  • Keyboard: key press, type text, shortcuts

• Added command-line options with parameters:

--click "selector"               Click element matching selector
--move <x> <y>                  Move mouse to coordinates
--drag "src" "target"           Drag element from source to target
--scroll <x> <y>                Scroll page by x,y pixels
--type "text"                   Type text
--key "keyname"                 Press a single key
--shortcut "combo"              Send keyboard shortcut

Example usage:

# Fill out a login form
mdx web get "https://example.com" \
  --click "#username" \
  --type "myuser" \
  --click "#password" \
  --type "mypass" \
  --click "#submit"

Added help documentation in web get inputs.txt with examples and usage info for each command.

Added test coverage in web-input-test.yaml to verify functionality.

Fixes #9.