Shared core spec: single source of logic (read/write, material, tag format)

[mateusdemboski]

Goal

Define a spec / mechanism so the main logic — read/write flow, material handling, tag (spoolData) format — is authored once and shared, instead of re-implemented per client.

Firmware is the source of truth today (owns AES keys, 48-char spoolData format, weight→length codes, UI lists). Desktop and web are thin clients that fetch UI lists at startup. Keep the web UI working the same way; minimize logic duplication as much as possible.

Scope

• Formalize the wire contracts (getspec//api/spec, write/read/status/config/db/ota) into a versioned spec doc.
• Identify any logic that currently risks duplication across firmware / desktop / web and pin it to one owner.
• Decide shared-artifact format (JSON schema? generated types?) consumable by desktop (Go) + web (TS).

Related: repo split (spec repo), Reader refactor.