[Feature]: Dogfood /constitution on spec-kit (add memory/constitution.md)

[PascalThuet]

Problem Statement

Spec-kit ships /constitution but the repo itself has no memory/constitution.md in main. There is no upstream artifact showing the workflow runs on the project that ships it — the dogfooding gap raised in discussion #2504. A maintainer (@mnriem) gave a green light to try it there, with the framing that specs in this repo should be spec-forward, historical-once-shipped (no living-doc maintenance burden against a fast-moving codebase).

Proposed Solution

Add memory/constitution.md, drafted via the /constitution workflow. It codifies:

• When SDD applies here: non-trivial scope, ambiguous design, cross-cutting impact, security/correctness stakes.
• When it does not: plumbing, refactors, catalog updates, doc fixes.
• Stance: spec-forward; historical once shipped (frozen snapshot, not maintained).

Single document. No quota, no cadence, no downstream commitment to spec any particular future PR.

Alternatives Considered

• Retroactive specs on shipped PRs (e.g. feat: Config-driven opt-in authentication registry with multi-platform support #2393): parked — does not fit "spec-forward."
• Per-feature triage on every PR: re-litigates the question on every change, more friction.
• Status quo: dogfooding gap remains.

Component

Documentation

AI Agent (if applicable)

Not applicable (repository governance, not agent-specific)

Use Cases

1. Contributor unsure whether their PR warrants a spec consults the constitution instead of asking per-PR.
2. Reviewer points to it to flag a fitting candidate ("cross-cutting and security-sensitive — want to spec this?").

Acceptance Criteria

• memory/constitution.md exists in main
• Drafted via the /constitution workflow
• Codifies criteria for when SDD applies to spec-kit work
• Codifies the "spec-forward, historical-once-shipped" stance per Proposal: dogfood Spec-Driven Development on features that warrant it #2504
• No downstream commitments added (no quota, no required follow-up specs)

Additional Context

Discussion #2504, in particular @mnriem's comment giving the green light and the spec-forward framing. PR follows.