Simplify circular dependency detection

[alganet]

• Used topological sort for all entries, not just constants
• Removed checks during instantiation, relying on instantiation-time check only.
• Updated tests and documentation.

Description

Brief description of changes.

Type of Change

• Bug fix
• Refactoring
• New feature
• Breaking change
• Documentation update

Checklist

• Descriptive and concise commit message and PR details
• Docstrings updated
• Documentation updated

[Copilot]

Pull request overview

This PR refactors circular dependency detection in apywire to occur at initialization time rather than at runtime. The key change moves from a runtime stack-based detection mechanism to an upfront topological sort of all spec entries during Wiring() construction.

Key changes:

• Circular dependencies are now detected during Wiring() initialization using Kahn's algorithm for topological sorting
• Removed runtime circular dependency checks and the resolving stack infrastructure from both thread-safe and non-thread-safe modes
• Generator silently stops recursion when cycles are detected, deferring error handling to the runtime container

Reviewed changes

Copilot reviewed 23 out of 23 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
apywire/wiring.py	Major refactoring: added SpecParser base class, implemented upfront topological sort for all entries, removed resolving stack logic
apywire/runtime.py	Removed runtime circular dependency checking (stack-based detection) from _instantiate_impl
apywire/threads.py	Removed resolving stack from thread-local state, keeping only lock-related state
apywire/generator.py	Changed from raising CircularWiringError to silently returning on cycles, inherits from SpecParser
tests/test_threading.py	Updated tests to expect CircularWiringError at init time instead of access time
tests/test_single.py	Updated tests to expect CircularWiringError at init time instead of access time
tests/test_constant_placeholders.py	Updated tests to expect CircularWiringError at init time instead of access time
tests/test_generator.py	Renamed _is_constant to _is_spec_constant, updated circular dependency test to verify silent return behavior
tests/test_internals.py	Removed tests for _get_resolving_stack (no longer needed)
tests/test_edge_cases.py	Removed resolving stack initialization tests
docs/user-guide/circular-dependencies.md	New guide documenting circular dependency detection behavior
docs/user-guide/*.md	Updated references to circular dependencies throughout documentation
docs/api-reference.md	Updated CircularWiringError example to show detection at init time
Makefile	Removed reuse dependency from format target

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[Copilot]

The code example uses pytest.raises but doesn't import pytest. The example should either import pytest at the top or use a try/except block like the first example to maintain consistency and ensure the code is runnable as shown.