feat(workspace): add hygiene report

[chubes4]

Summary

• Adds a non-destructive workspace hygiene report that surfaces workspace size, free disk, worktree counts, and local cleanup candidates.
• Provides both on-demand CLI/ability access and an opt-in weekly system task for recurring visibility.
• Keeps the default report bounded and local-only so it does not require GitHub lookups or perform cleanup.

Changes

• Adds wp datamachine-code workspace hygiene with table and JSON output, plus --skip-cleanup, --skip-sizes, and --size-limit options.
• Registers datamachine/workspace-hygiene-report for agent/runtime use.
• Adds workspace_hygiene_report as a disabled-by-default system task and weekly recurring schedule.
• Reuses existing worktree listing and cleanup dry-run logic, enriching cleanup candidates with best-effort size data when available.
• Adds focused smoke coverage for CLI rendering and task gating/completion behavior.

Incident context

• On 2026-04-29, the local workspace fell to about 1.1 GiB free because stale worktrees grew to roughly 712.6 GiB.
• This report is intended to make that class of disk-pressure failure visible before cleanup becomes urgent, while keeping the default path review-only and non-destructive.

Tests

• php -l data-machine-code.php inc/Abilities/WorkspaceAbilities.php inc/Cli/Commands/WorkspaceCommand.php inc/Workspace/Workspace.php inc/Tasks/WorkspaceHygieneReportTask.php tests/smoke-workspace-hygiene-cli.php tests/smoke-workspace-hygiene-task.php
• php tests/smoke-workspace-hygiene-cli.php
• php tests/smoke-workspace-hygiene-task.php
• php tests/smoke-worktree-cleanup-cli.php
• git diff --check
• homeboy lint data-machine-code --path /Users/chubes/Developer/data-machine-code@feat-workspace-hygiene-report --file inc/Tasks/WorkspaceHygieneReportTask.php --summary
• homeboy lint data-machine-code --path /Users/chubes/Developer/data-machine-code@feat-workspace-hygiene-report --file tests/smoke-workspace-hygiene-cli.php --summary
• homeboy lint data-machine-code --path /Users/chubes/Developer/data-machine-code@feat-workspace-hygiene-report --file tests/smoke-workspace-hygiene-task.php --summary

Full scoped lint on the broader touched legacy files still reports pre-existing PHPStan/PHPCS drift in Workspace.php, WorkspaceCommand.php, WorkspaceAbilities.php, and data-machine-code.php; the new task and smoke files are clean.

Closes #146

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Implemented the workspace hygiene report, CLI/ability/task wiring, smoke tests, and PR description. Chris remains responsible for review and merge.