[codex] implement MyPayTag SDK sprint 7 contracts

[KazanderDad]

What changed

Implemented the Sprint 7 MVP gap-closure contract work for MyPayTag SDK:

• Added dedicated NEAR Intents / 1Click MVP quote, selected-quote, and payable-instruction protocol contracts.
• Moved generic solver fanout to Phase 2 and kept NEAR 1Click on dedicated MVP helpers.
• Tightened provider callback binding across resolver request, route, amount, purpose, expiry, PayingDapp id/reference, and provider intent id.
• Aligned OpenAPI/Postman examples with canonical protocol validators.
• Added route CRUD and hosted route-selection action schemas, fixtures, validators, provider SDK helpers, and tests.
• Documented paytag availability as a private MyPayTag/Cubid service boundary while keeping public-safe testing fixtures.
• Expanded MVP fixtures and runnable PayingDapp/PayToDapp examples.
• Stabilized generated Postman example normalization to avoid random numeric/boolean faker drift.

Why

The revised MVP promotes NEAR Intents / 1Click into the Phase 1 swap/bridge path and needs SDK contracts that backend, site, PayingDapp, PayToDapp, and staging smoke tests can share without exposing Cubid internals, wallet graph data, route preferences, or private diagnostics.

Impact

SDK consumers now have canonical generated types, validators, fixtures, docs, OpenAPI examples, Postman output, and runnable examples for the Sprint 7 MVP paths. Broad solver fanout remains available only as a Phase 2 extension helper.

Validation

• pnpm generate
• pnpm api:postman
• pnpm validate
• pnpm api:validate

Full validation regenerated types, linted OpenAPI without warnings, built/typechecked all packages, passed tests with 59 workspace cases, passed the public-boundary scan, cleaned, and rebuilt.

[KazanderDad]

@codex review