Track Superpowers-inspired Base workflow adoption

[codeforester]

Problem

The obra/superpowers repository has several useful agent-workflow practices, but Base should adopt them selectively and adapt them to Base's product boundaries, issue-first GitHub workflow, sibling worktree convention, and validation habits.

Reference:

• https://github.com/obra/superpowers

Desired Outcome

Track the Base adoption of Superpowers-inspired practices as a small, concrete issue set rather than a broad methodology migration.

Scope

Coordinate these follow-up issues:

• Adopt Base-specific debugging and verification guidance #500
• Adapt worktree lifecycle guidance from Superpowers #501
• Define Base skill-authoring guidance #502
• Define Base test-first and review-feedback guidance #503

Non-Goals

• Do not vendor or require the Superpowers plugin.
• Do not switch Base to the Superpowers docs directory layout.
• Do not replace Base's basectl gh, AGENTS.md, skills.md, or ~/work/base-worktrees/<slug> conventions.
• Do not apply strict Superpowers rules to every small docs or config change.

Acceptance Criteria

• Each linked issue is completed, explicitly superseded, or closed with a documented reason.
• The adopted practices are represented in the right Base layer: skills.md, AGENTS.md, CONTRIBUTING.md, or focused docs as appropriate.
• The final outcome keeps Base focused as a local workspace control plane.
• The final summary identifies which Superpowers practices Base adopted, adapted, or rejected.

Validation

• Validation belongs to the linked issues.
• This tracker can close once the linked issue set is resolved or intentionally pruned.

Demo Impact

None. Process/backlog tracking only.