feat(telemetry): measure scan and hub export

[kevinmessiaen]

Description

Giskard OSS can now measure whether developers start and complete quality or vulnerability scans, and whether Checks results are prepared for Hub. These signals support the OSS vision's activation and paid-intent measures without collecting prompts, outputs, scenario content, names, paths, or arbitrary caller strings.

Caller-controlled telemetry values are constrained at runtime: modes and booleans use allowlists, requested scenario counts use fixed buckets, and scan results contain aggregate counts and duration only. This PR deliberately does not claim Scan-to-Checks conversion because OSS has no explicit promotion action that can be measured reliably.

Validation:

• Giskard Scan unit suite: 180 passed, 44 skipped, 2 deselected.
• Giskard Checks unit suite: 951 passed, 4 skipped.
• Formatting, linting, Python compatibility, type checking, license checks, and extra-pin checks passed.
• make check reaches the security audit and fails on the pre-existing nltk==3.10.0 advisory PYSEC-2026-3726; the published fix is 3.10.2.
• Independent privacy and code review approved the final implementation.

Related Issue

No linked issue.

Type of Change

• 📚 Examples / docs / tutorials / dependencies update
• 🔧 Bug fix (non-breaking change which fixes an issue)
• 🥂 Improvement (non-breaking change which improves an existing feature)
• 🚀 New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 🔐 Security fix

Coding agents

The autonomous-agent instructions in AUTONOMOUS.md were followed. The agent-local plan remains uncommitted.

Checklist

• I've read the CODE_OF_CONDUCT.md document.
• I've read the CONTRIBUTING.md guide.
• I've written tests for all new methods and classes that I created.
• I've written the docstring in NumPy format for all the methods and classes that I created or modified.
• I've updated the uv.lock running uv lock (only applicable when pyproject.toml has been modified)