chore: refresh OpenAPI spec + managedBy on RG/SP/AlertChannel

[caballeto]

Summary

After mono#369 merged and dispatched spec_updated, the CLI's spec-check (and downstream npm test) ran red because:

1. The bundled spec was stale — missing managedBy on Create* / Update* DTOs for ResourceGroup, StatusPage, and AlertChannel (added for attribution parity with Monitor); missing currentStatus on MonitorDto.
2. The field-parity audit (test/yaml/spec-field-parity.test.ts) saw the new managedBy API field with no entry in API_ONLY_FIELDS for those three resource families and failed the audit.
3. test/commands/monitors-test-config.test.ts deliberately omitted managedBy to trigger a Zod error; that field is now optional (server defaults to API / surface-injected value), so the assertion expect(out).toContain('managedBy') no longer matched the actual error.

This PR fixes the immediate spec-check breakage and the v0.7.0 resource-groups list bug that started this whole sprint (strict Zod was rejecting the production API's new managedBy response field).

Changes

• Refresh docs/openapi/monitoring-api.json from the live mono spec.
• Regenerate src/lib/api.generated.ts, api-zod.generated.ts, spec-facts.generated.ts, descriptions.generated.ts, and the skill field references.
• Inject managedBy: 'CLI' in YAML transforms for AlertChannel, ResourceGroup, and StatusPage so resources created via devhelm apply get correct attribution. Mirrors the existing Monitor transform pattern; the snapshot diffs already exclude managedBy so we don't fight the dashboard on subsequent updates.
• Add managedBy to API_ONLY_FIELDS for alertChannel, resourceGroup, and statusPage in the field-parity test — the CLI sets it internally and YAML users must not author it.
• Pivot the malformed-config test fixture to omit the still-required name field so we keep a stable, typed Zod error path.

Why managedBy on those three resources is API-only (not YAML)

managedBy is a provenance signal owned by the surface, not declarative state authored by the user. If a YAML config drops the field, the CLI should still stamp CLI; if the user explicitly wrote managedBy: TERRAFORM we would want to reject it because YAML files belong to the CLI. Marking it API-only enforces that contract.

Test plan

• regen all generated artefacts; in sync
• npm test → 998/998 pass (was 994/998 before)
• npm run lint clean
• npm run typecheck clean
• npm run build succeeds
• After merge: cut v0.7.1 to fix v0.7.0 resource-groups list bug + ship currentStatus + correct managedBy attribution.

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