feat: add Rust postprocess kernel

[MapleEve]

Summary

• Add a pure Python postprocess oracle for result segment assembly, display-name disambiguation, conservative text-only segment merge, and JSON-safe word normalization.
• Add the matching Rust postprocess kernel and Python bridge entrypoint for RUST_KERNEL_MODE=required, while keeping the default Python path.
• Extend Docker heavy-gate smoke, changelog, configuration docs, and unit coverage for the new selected Rust-backed path.

Validation

• PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 python -m pytest tests/unit/ tests/test_security.py tests/test_voiceprint_db.py tests/test_job_service.py -q --tb=short
• cargo fmt --manifest-path crates/voscript_core/Cargo.toml -- --check
• cargo test --manifest-path crates/voscript_core/Cargo.toml
• cargo clippy --manifest-path crates/voscript_core/Cargo.toml --features python-bindings --all-targets -- -D warnings
• ruff format --check app/ tests/unit/test_kernel_bridge.py tests/unit/test_pipeline_alignment.py tests/unit/test_pipeline_runner.py tests/unit/test_postprocess_segments_kernel.py
• ruff check app/ tests/unit/test_kernel_bridge.py tests/unit/test_pipeline_alignment.py tests/unit/test_pipeline_runner.py tests/unit/test_postprocess_segments_kernel.py --ignore E501
• python voscript-api/scripts/public_release_scan.py --root <repo>
• git diff --check

Notes

• Public HTTP schema stays unchanged.
• speaker_label remains the stable cluster key; duplicate display names are disambiguated, not merged.
• segments[].words remains optional.

[claude]

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[Copilot]

Pull request overview

This PR introduces a deterministic, side-effect-free transcript post-processing “oracle” in Python and a matching Rust kernel (exposed via the existing providers.kernel_bridge) so RUST_KERNEL_MODE=required runs can hard-require native post-processing while keeping the default Python execution path.

Changes:

• Added pure Python post-processing helpers for segment assembly, display-name disambiguation, conservative text-only merging, and JSON-safe word normalization.
• Added a Rust post-processing implementation plus PyO3 bindings and Python bridge validation/entrypoint.
• Extended unit tests, docs/changelog, environment/config documentation, and Docker heavy-gate smoke to cover the new Rust-backed path.

Reviewed changes

Copilot reviewed 19 out of 20 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/unit/test_postprocess_segments_kernel.py	New golden tests for the Python postprocess oracle behaviors (normalization, merging, display names, segment assembly).
tests/unit/test_pipeline_runner.py	Adds coverage ensuring artifacts provider selects Rust postprocess when RUST_KERNEL_MODE=required.
tests/unit/test_pipeline_alignment.py	Formatting-only updates to existing assertions.
tests/unit/test_kernel_bridge.py	Updates expected core version and adds bridge tests for postprocess_segments validation.
doc/configuration.zh.md	Documents that RUST_KERNEL_MODE now also selects result post-processing.
doc/configuration.en.md	Same as above (English).
doc/changelog.zh.md	Changelog entry for Rust-backed result post-processing + related coverage updates.
doc/changelog.en.md	Same as above (English).
crates/voscript_core/src/postprocess.rs	New Rust implementation for merging/normalizing aligned segments and building result segments.
crates/voscript_core/src/lib.rs	Exposes Rust postprocess via PyO3 (postprocess_segments) and parsing helpers.
crates/voscript_core/Cargo.toml	Bumps voscript_core version to 0.8.2.
Cargo.lock	Locks the updated voscript_core version.
app/providers/kernel_bridge/runtime.py	Adds Rust postprocess response validation and Python bridge entrypoint postprocess_segments.
app/providers/kernel_bridge/init.py	Re-exports postprocess_segments.
app/providers/artifacts/default.py	Switches segment assembly to Python oracle by default and Rust kernel when required.
app/postprocess/segments.py	New Python oracle module for post-processing logic used by both pipeline and Rust equivalence tests.
app/postprocess/init.py	Exposes the postprocess helpers as a package API.
app/pipeline/stages/diarization/alignment.py	Reuses the shared normalize_words helper from the new postprocess module.
.github/workflows/rust-foundation-heavy.yml	Extends Docker heavy-gate smoke to exercise postprocess_segments under required mode.
.env.example	Notes that required Rust mode now covers result post-processing in addition to voiceprint scoring.

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[codecov]

Codecov Report

❌ Patch coverage is 84.56790% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.22%. Comparing base (259f0bb) to head (e8dbeaa).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
app/providers/kernel_bridge/runtime.py	68.05%	23 Missing ⚠️
app/postprocess/segments.py	98.75%	1 Missing ⚠️
app/providers/artifacts/default.py	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #37      +/-   ##
==========================================
- Coverage   91.59%   91.22%   -0.38%     
==========================================
  Files          79       81       +2     
  Lines        3333     3464     +131     
==========================================
+ Hits         3053     3160     +107     
- Misses        280      304      +24     

Flag	Coverage Δ
unit	91.22% <84.56%> (-0.38%)	⬇️

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