Attach the lifecycle to existing nested and lazy Click command trees

[codeforester]

Parent: #50

Train position: 7 of 22
Phase: P1 — Incremental adoption

Problem

Adoption currently requires rebuilding commands around App; established Click applications need an incremental, composition-preserving integration path.

Acceptance criteria

• A public attach(click.Command) API and/or lifecycle-aware Click Command/Group classes preserve callbacks, parameters, context settings, names, help, and third-party commands.
• Nested groups, aliases, prebuilt commands, and lazy command providers work without eager import or enumeration.
• Lifecycle middleware and an optional context/service factory are available at documented extension points.
• The lifecycle runs exactly once for the selected leaf without duplicate standard options.
• Representative existing Click trees are integration-tested.

Dependencies

• Make lifecycle teardown failure-safe #51
• Unify production and test invocation and restore native Click option syntax #53
• Repair application naming and registration contracts #55