Clarify hygiene inventory blocker counts

[chubes4]

Summary

• label hygiene dirty counts as inventory-known counts when they come from cheap inventory rows
• split blocker counts into inventory-known and fresh-probed buckets in hygiene output
• update compact hygiene output coverage for the explicit probe-source fields

Closes #825.

Tests

• php -l inc/Workspace/WorkspaceHygieneReport.php && php -l inc/Cli/WorkspaceCompactOutput.php && php -l inc/Cli/Commands/WorkspaceCommand.php && php -l tests/workspace-compact-output.php
• php tests/workspace-compact-output.php && php tests/workspace-hygiene-timeout-safe-contract.php && php tests/worktree-cleanup-candidate-classifier.php && php tests/bounded-cleanup-processed-candidates.php && php tests/cleanup-remaining-work-summary.php && php tests/worktree-disk-budget.php

AI assistance

• AI assistance: Yes
• Tool(s): openai/gpt-5.5 via OpenCode
• Used for: Implementing the hygiene reporting change, updating focused coverage, and running verification.