Provide an optional batteries-included configuration profile

[codeforester]

Parent: #50

Train position: 10 of 22
Phase: P1 — Incremental adoption

Problem

The generic profile should stay convention-free, but adopters need a well-defined optional configuration stack rather than reimplementing common policy.

Acceptance criteria

• An opt-in profile supplies platform-aware user, project, environment, and explicit configuration layers.
• Precedence, merging, provenance, validation, and environment selection are deterministic and documented.
• Validated framework lifecycle settings are separated from opaque consumer configuration.
• Missing optional layers are allowed while explicit paths remain strict.
• CliProfile.generic() stays convention-free and dependency-light.

Dependencies

• Reject missing explicit configuration files #56
• Publish stable typed runtime, profile, and context extension contracts #59