Step 1: FCPTime and unused value types

[leogdion]

What to build

Introduce the shared attribute-value machinery and strong types (FCPTime, bools, DTD enums, resource id/ref types) with unit tests only — nothing in the Codable model references them yet.

Acceptance criteria

• FCPTime round-trips fixture forms byte-identically (5s, 0s, 1001/30000s, 22800/2400s) and rejects illegal strings
• Equality ignores rendering form; arithmetic is exact and does not emit decimal seconds
• Bool / enum / id types encode as single-value strings compatible with existing XMLCoder node encoding
• Unknown enum values can pass through on decode; strict mode is defined and tested (even if unused by the model yet)
• No production call sites migrate onto these types in this ticket
• swift test and schema-completeness at 0 remain green

Blocked by

• Step 0: XMLCoder ordering guardrails + Spine choice spike #5 Step 0: XMLCoder ordering guardrails + Spine choice spike

References

• Plan: docs/planning/v0.1.0-first-working-version.md
• ADR: docs/adr/0002-create-first-ordered-typed-model.md
• Worktrees: docs/planning/v0.1.0-worktree-plan.md

[leogdion]

Step 1 implementation is up: #18 — Sources/FCPKit/Values/ (XMLAttributeValue machinery, FCPTime, FCPBool, DTD enums with unknown pass-through + strict mode, ResourceID/ResourceRef) plus 44 Swift Testing tests. Full gate green: strict lint 0 violations, swift build/test pass, schema-completeness 0.