Adopt the repository specification standard: SPEC.md

[PaulSnow]

Every repository under active development carries a normative SPEC.md.

Standard: https://github.com/PaulSnow/tracking_repo/blob/main/docs/standards/spec-driven-development.md
Reference implementation: adex documents/SPEC.md

Requirements:

• SPEC.md in the repo's documentation directory (documents/ or docs/, whichever the repo uses; create docs/ if neither). Never at the repository root.
• Two sections:
  1. Architecture — what we are doing: purpose, surfaces, objects, invariants. Readable without the code.
  2. Specification — how it is implemented: layout, components, interfaces, data flows, deployment. Every architectural claim in section 1 traces to a mechanism in section 2.
• CLAUDE.md opens with the normative hook:
  • ALL work is done against the spec — read the relevant section first; a change that contradicts the spec means fixing the spec or the plan first.
  • New work requires updating the spec — same MR/change set, not "later".

Acceptance:

• SPEC.md written (both sections), describing the system as it is
• CLAUDE.md hook added
• Gaps found while writing the spec filed as issues, not silently fixed