feat(contracts): add universal local connector contracts

[enricopiovesan]

Summary

• Add universal local connector contracts for object storage, state storage, and scheduling.
• Extend connector contracts with validated operation envelopes covering request schemas, success schemas, and stable failure classes.
• Register and validate the universal connector IDs alongside existing reference connectors.

Governing Spec

• 039-connector-plugin-architecture
• 014-service-type-taxonomy
• 056-capability-publish
• 103-application-connector-binding
• 104-mediated-connector-invocation
• 534-ecca-event-products

Project Item

• Closes Add universal local connector contracts and registry entries #1080

Definition of Done

• New connector contracts are checked in under contracts/connectors/.
• Reference connector registry exposes the new connector IDs.
• Validation rejects malformed connector schemas, semver, placement targets, and operation envelopes.

Validation

• cargo test -p traverse-contracts
• cargo clippy -p traverse-contracts --all-targets -- -D warnings
• BASE_SHA=$(git rev-parse origin/main) bash scripts/ci/spec_alignment_check.sh /private/tmp/pr-1080-body.md
• bash scripts/ci/coverage_gate.sh