…essaging

- Add descriptive timeout message to WaitTimeout exception
- Ensure consistent handling of timeout errors
- Fix type hints for function return values

…I and multi-pattern support

- Implement Playwright-inspired fluent API for more expressive test code
- Add wait_for_any_content and wait_for_all_content for composable waiting
- Fix type annotations for all wait_for functions
- Improve WaitResult class to handle different return types
- Fix doctest examples to prevent execution failures
- Enhance error handling with better timeout messages

- Fix test_wait_for_pane_content_exact to use correct match type
- Update test_wait_for_any_content to check matched_pattern_index
- Fix test_wait_for_all_content to handle list of matched patterns
- Add comprehensive type annotations to all test functions
- Ensure proper handling of None checks for Pane objects

…iters

- Create detailed markdown documentation in docs/test-helpers/waiter.md
- Add key features section highlighting main capabilities
- Include quick start examples for all functions
- Document fluent API with Playwright-inspired design
- Explain wait_for_any_content and wait_for_all_content with practical examples
- Add detailed API reference for all waiters
- Include testing best practices section

- Adds a conftest.py file in tests/examples to register the pytest.mark.example marker
- Eliminates pytest warnings about unknown markers in example tests
- Improves test output by removing noise from warnings

- Each test file focuses on a single feature or concept of the waiter module
- Added descriptive docstrings to all test functions for better documentation
- Created conftest.py with session fixture for waiter examples
- Added helpers.py with utility functions for the test examples
- Test files now follow a consistent naming convention for easier reference
- Each test file is self-contained and demonstrates a single concept
- All tests are marked with @pytest.mark.example for filtering

This restructuring supports the documentation update to use literalinclude directives,
making the documentation more maintainable and ensuring it stays in sync with actual code.

Fixes test_wait_for_pane_content_exact_match_detailed failure on tmux 3.1b
where capture_pane() was called immediately after send_keys() before the
content had been flushed/rendered by tmux.

The race condition manifested as:
  AssertionError: assert 'UNIQUE_TEST_STRING_123' in ''

Adding a 0.1s delay after send_keys() allows tmux to flush the content
before capture_pane() is called, fixing the timing issue on older versions.

why: test_wait_for_any_content_exact_match was flaky due to race
condition - pane content captured before terminal finished redrawing
after clear command.
what:
- Add wait_until_pane_ready() after send_keys("clear") to ensure
  shell prompt is ready before capturing content
- Uses idiomatic waiter pattern instead of arbitrary time.sleep()

why: Test was unreliable because shell prompts vary by environment
what:
- Replace prompt detection ($, %, >, #) with echo marker pattern
- Remove skip decorator - test now runs reliably
- Simplify test logic by using deterministic output

why: Module had no direct tests, only indirect coverage via waiter mocking
what:
- Test immediate success (returns True on first call)
- Test success after multiple retries
- Test timeout with raises=True (raises WaitTimeout)
- Test timeout with raises=False (returns False, WaitTimeout)

why: test_wait_for_pane_content_exact_match_detailed is flaky on tmux 3.4
due to capture-pane line wrapping behavior differences introduced in that
version (commit 9cc8e40a added GRID_STRING_EMPTY_CELLS flag)
what:
- Add pytest.mark.skipif to skip test on tmux 3.4 specifically
- Import has_version for exact version checking

why: Sphinx autodoc failed with ModuleNotFoundError
what:
- Change libtmux.test.retry_extended to libtmux._internal.retry_extended