AMPR-165 #489: Finish declarative spark migration

[wow-miley]

Closes #489.

This PR finishes AMPR-165 by moving the remaining role, language, and Ampere project sparks into JSON-frontmatter fixtures and removing the hard-coded RoleSpark hierarchy. It extends the spark parser/registry with role, language, and project lookup surfaces, adds sensitive-file forbiddenRefs, and wires factories/Arc spawning to resolve declarative sparks. Tests cover fixture equivalence, parser variants, registry lookup, factory fail-fast behavior, and Ampere project interpolation. Validated with ./gradlew ktlintFormat, ./gradlew jvmTest, and git diff --check.

[github-actions]

Concept staleness check — 1 warning(s).

These changes touched files listed under a concept's tracked_sources without updating the concept file. Either update the concept (and bump last_verified) or include a Concept-Verified: <ConceptName> trailer in a commit on this PR.

Validator output

⚠ Concept 'EventSerialBus' may be stale: ampere-core/src/commonMain/kotlin/link/socket/ampere/agents/domain/event/SparkEvent.kt matches tracked_sources pattern ampere-core/src/commonMain/kotlin/link/socket/ampere/agents/domain/event/** but docs/concepts/event-serial-bus.md was not modified.

validate-concepts: 1 warning(s). Validator informs; never blocks.