Add crates.io ecosystem intelligence CLI

Goal

Add a Printing Press CLI for crates.io package intelligence.

Free source

• crates.io public API.

Agent jobs

• Evaluate Rust crate health before adoption.
• Compare crates by downloads, freshness, owners, features, and dependency shape.
• Track release cadence and recently updated crates in a category.

Proposed command shape

• crates-intel-pp-cli crate tokio --agent
• crates-intel-pp-cli compare reqwest ureq isahc --agent
• crates-intel-pp-cli downloads tokio --agent
• crates-intel-pp-cli releases serde --since 180d --agent
• crates-intel-pp-cli deps axum --agent

Non-goals

No publishing, yanking, owner changes, or token-authenticated mutation.\n\n## Implementation path\n\nThis is a new CLI candidate, so do not hand-build it directly in this published library repo. Run it through the canonical Printing Press generation flow in cli-printing-press, keep manuscripts/proofs, then publish into this repo with the publish flow.\n\n## Acceptance criteria\n\n- Research notes explain the source/API/feed contract, rate limits, auth needs, and freshness behavior.\n- CLI exposes a small agent-native command set, not a raw endpoint dump.\n- --json / --agent output is stable and compact.\n- If the source benefits from history, add local SQLite sync plus since/diff commands.\n- Skill includes high-signal recipes and clear non-goals.\n- Dogfood proves at least three realistic agent workflows.