feat: add compute_output_permutation utility

[dlyongemallo]

Relates to #18.

[Copilot]

Pull request overview

Adds a new utility to read the qubit output permutation left behind by PyZX extraction when using up_to_perm=True, along with unit tests intended to validate the behavior.

Changes:

• Add compute_output_permutation(g) utility in zxpass/zxpass.py.
• Add tests for basic permutation properties, identity case, and a “matches swaps” scenario.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
zxpass/zxpass.py	Introduces compute_output_permutation to derive output→input mapping from a post-extraction graph.
test/test_zxpass.py	Adds new tests covering the new permutation utility and extraction behavior.

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[Copilot]

Pull request overview

Adds a small utility to interpret PyZX’s post-extraction boundary connectivity as an explicit qubit permutation, with accompanying unit tests to validate behavior against extract_circuit(up_to_perm=...).

Changes:

• Add compute_output_permutation() to derive an output→input qubit index mapping from a post-extraction PyZX graph.
• Add tests exercising the utility on reduced/extracted graphs and cross-checking against SWAP insertion behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
zxpass/zxpass.py	Introduces compute_output_permutation() with validation and error reporting.
test/test_zxpass.py	Adds tests for the new permutation utility, including an equivalence check via SWAP reconstruction.

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[Copilot]

Pull request overview

Adds a small helper utility to interpret PyZX’s post-extraction boundary graph connectivity and expose the resulting output-to-input qubit permutation, with accompanying tests to validate expected behavior and error handling.

Changes:

• Add compute_output_permutation(g) to derive {output_qubit_index: input_qubit_index} from a post-extraction graph (up_to_perm=True).
• Add unit tests covering normal operation, identity cases, SWAP equivalence, and several invalid-graph error branches.
• Update test module imports/lint settings to support the expanded test suite.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
zxpass/zxpass.py	Introduces compute_output_permutation utility for reading boundary connectivity after PyZX extraction.
test/test_zxpass.py	Adds a comprehensive test suite for the new utility, including error-case validation.

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