Fix example bugs, improve docs, and add copilot instructions

[cgillum]

Summary

While testing the examples against the local DTS emulator, several bugs were found and fixed.

Bug Fixes

Framework fix in durabletask/worker.py:

• The entity method dispatcher always passed entity_input as an argument to class-based entity methods, even when no input was provided. Methods like def get(self): that don't accept input would fail with TypeError: Counter.get() takes 1 positional argument but 2 were given. Fixed by using inspect.signature() to check whether the method accepts parameters before passing the argument.

Example fixes:

• function_based_entity.py: Changed if to elif for the set operation — it was falling through to the else branch and raising ValueError
• function_based_entity_actions.py: Added missing add operation handler
• sub-orchestrations-with-fan-out-fan-in/worker.py and orchestrator.py: Changed hardcoded secure_channel=True to dynamic detection based on endpoint, so these examples work with the local emulator

Documentation Improvements

• Rewrote examples/README.md with proper markdown formatting, added virtual environment setup instructions, local dev install steps, and PowerShell equivalents for multiline commands
• Added .github/copilot-instructions.md with project conventions
• Added .pymarkdown.json config and pymarkdownlnt to dev-requirements.txt for markdown linting

Testing

All 10 examples verified passing against the local DTS emulator. All 13 unit tests pass. Also added 5 new unit tests for entities, which are passing.

[Copilot]

Pull request overview

This PR fixes a class-based entity dispatch bug in the core worker, updates several examples to run correctly against the local DTS emulator, and improves repository documentation and Markdown linting support.

Changes:

• Fix _EntityExecutor to only pass entity_input to class-based entity methods when the method accepts an input parameter.
• Correct example entity handlers and update sub-orchestration examples to avoid hardcoded TLS configuration.
• Refresh examples/README.md formatting/instructions and add Copilot + Markdown linting configuration.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
durabletask/worker.py	Adjusts class-based entity method invocation to avoid passing input to no-arg operations.
tests/durabletask/test_entity_executor.py	Adds unit tests for class-based entity dispatch behavior (and function-based coverage).
examples/entities/function_based_entity.py	Fixes control-flow bug (if → elif) in the entity operation handler.
examples/entities/function_based_entity_actions.py	Adds missing "add" operation handler in the entity example.
examples/sub-orchestrations-with-fan-out-fan-in/worker.py	Makes secure_channel selection configurable based on endpoint.
examples/sub-orchestrations-with-fan-out-fan-in/orchestrator.py	Makes client secure_channel selection configurable based on endpoint.
examples/README.md	Rewrites example documentation with improved Markdown and setup/run instructions.
dev-requirements.txt	Adds pymarkdownlnt to dev dependencies.
.pymarkdown.json	Adds Markdown lint configuration.
.github/copilot-instructions.md	Adds repository conventions and guidance for Copilot usage.

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