v0.2: zero-friction usage governor

[ctdaniel]

Summary

Codex Quota Optimizer 0.2 evolves the project from a static usage policy into a lightweight, optional usage governor without putting anything in Codex's critical path.

Zero-friction principles

• 0 additional model calls just to classify/budget a task
• 0 network requests for CQO runtime behavior
• 0 blocking budget gates
• 0 forced confirmations when a soft budget is exceeded
• 0 automatic subagents from CQO itself

Added

• Local heuristic Task Classifier (English + Chinese signals)
• Soft Session Budgets
• Local-only task journal under ~/.cqo / CQO_HOME
• Honest task-level Usage Audit
• Optional cqo start / status / audit / history CLI
• Unit tests + CLI smoke-test workflow
• Zero-friction policy reference

Changed

• Budgets are explicitly advisory; correctness can expand scope without interruption.
• The CLI is optional observability, not a runtime dependency.
• Direct install.sh also exposes ~/.local/bin/cqo.
• Plugin manifests bumped to 0.2.0.

Validation

Local implementation smoke tests passed before submission. This PR also runs the standard HOL Plugin Scanner and the new Python CLI test workflow.

Note: the existing HOL catalog PR (#421 in hashgraph-online/awesome-codex-plugins) is still open, so keeping this release in a source PR until catalog admission settles avoids changing the already-scanned default branch underneath that contribution.