feat: add assignment submission scoring

[Siddhant-K-code]

Description

Closes #213.

Adds privacy-minimized assignment submissions and deterministic local scoring for agent-based technical hiring workflows:

• agent-strace share --assignment [SESSION_ID] --output submission.zip
• agent-strace score SUBMISSION.zip --rubric FILE
• bounded directory comparison with --compare
• versioned JSON output with stable ties and opaque submission labels
• strict six-member assignment-v1 ZIP schema with relative timestamps, anonymous references, frozen pricing/lint/viewer semantics, and internal SHA-256 consistency checks
• hostile-input validation without archive extraction
• documented human-review and privacy limitations
• checked-in rubric, synthetic generator, and reviewable golden submission members

Assignment bundles intentionally omit raw identity, prompts, results, commands, paths, file contents, environment values, URLs, and custom model identifiers. Scores are deterministic process-telemetry arithmetic for human review, not hiring decisions or task/candidate-quality judgments. Bundle hashes provide consistency, not signatures or provenance.

Validation

• Ona Test task: 1,895 Python tests passed
• VS Code extension: 3 tests passed
• Ona Build task passed; wheel built as agent_strace-0.93.0-py3-none-any.whl
• Focused assignment suite: 26 tests passed
• Two independent reviews approved with no blockers
• Compile, CLI help, example generation/scoring, golden compatibility, and git diff --check passed

Release

This feature bumps the package from 0.92.0 to 0.93.0 following the repository's minor-version policy.

[Siddhant-K-code]

Independent review: approved with no blockers.

Reviewed the complete PR against #213, including CLI behavior, the assignment-v1 data contract, privacy minimization, strict archive/rubric validation, deterministic weighted scoring and ranking, compatibility-frozen assets/pricing/lint semantics, docs, examples, and the v0.93.0 bump.

Validation evidence:

• Hosted CI is green on Python 3.10, 3.11, 3.12, and 3.13
• Hosted VS Code extension check is green
• Settled-tree Ona test task: 1,895 Python tests and 3 extension tests passed
• Focused assignment suite: 26/26 passed
• Ona build task passed and built the 0.93.0 wheel
• Two independent reviewers found no remaining blockers

Security/privacy review confirmed that decompressed bundle members omit raw identity, prompts, results, commands, paths, file contents, environment values, URLs, credentials, and custom model identifiers. Reports clearly state that scoring is a human review aid, not an automated hiring decision or a task/candidate-quality measure.

Approved for squash merge.