examples: add task-oriented examples (form fill, table scrape)

[sujithps]

Summary

examples/ has a single hello-world (quickstart.py). Newcomers learn faster from short, task-shaped examples that map to real use.

Scope

Add 2-3 small, self-contained Python scripts under examples/, each runnable and heavily commented:

• fill_form.py — navigate to a form, fill fields, submit, read the result.
• scrape_table.py — extract an HTML table into a list of dicts.
• screenshot_element.py — screenshot a single element by selector.

Prefer stable targets: a local HTML fixture or example.com, not a third-party site that may change or bot-block.

Acceptance criteria

• Each script runs top to bottom with no arguments.
• Each has a one-line docstring stating what it demonstrates.
• No dependency on a flaky external site.

Pointers

• Style: examples/quickstart.py.
• Local fixtures: mcp/tests/fixtures/ shows the pattern.

Proposed as a good first issue; a maintainer will apply the label.