Add DIBBS, SBIR, and exclusions coverage (Tango v4.18 surfaces)

[makegov-mark]

Tango ships three resource families that this SDK has no client methods for: DIBBS, SBIR/STTR, and exclusions. They landed in Tango v4.18, are fully documented on docs.makegov.com, and are already implemented in tango-python — this SDK is the one that didn't get them.

Why

The gap is silent. Nothing in this repo checks client coverage against Tango's registered routes, so these surfaces have been missing without failing anything. For comparison, the docs repo does have such a gate (scripts/check_api_drift.py) — which is why the docs are current and the SDK isn't.

Practical effect: a Node consumer who wants DLA solicitation data, SBIR topics, or SAM exclusion records has to drop to raw HTTP, and tango-node is at 1.1.0 against tango-python 1.4.0.

Missing endpoints

Resource	Endpoints	Docs
DIBBS RFQs	GET /api/dibbs/rfqs/, GET /api/dibbs/rfqs/{id}/	dibbs
DIBBS RFPs	GET /api/dibbs/rfps/, GET /api/dibbs/rfps/{id}/	dibbs
DIBBS awards	GET /api/dibbs/awards/, GET /api/dibbs/awards/{id}/	dibbs
SBIR topics	GET /api/sbir/topics/, GET /api/sbir/topics/{id}/	sbir
SBIR solicitations	GET /api/sbir/solicitations/, GET /api/sbir/solicitations/{id}/	sbir
Exclusions	GET /api/exclusions/, GET /api/exclusions/{id}/	exclusions

Route definitions in Tango: src/dibbs/urls.py, src/sbir/urls.py, src/exclusions/urls.py.

Reference implementation

tango-python v1.4.0 tango/client.py — mirror these, including filter params and shape handling:

• list_dibbs_rfqs / get_dibbs_rfq
• list_dibbs_rfps / get_dibbs_rfp
• list_dibbs_awards / get_dibbs_award
• list_sbir_topics / get_sbir_topic
• list_sbir_solicitations / get_sbir_solicitation
• list_exclusions / get_exclusion

Current state in this repo

src/client.ts has 83 resource methods. dibbs and sbir appear nowhere in src/. exclusion appears only in src/shapes/explicitSchemas.ts — a shape schema with no client method behind it, so the type exists but is unreachable.

Note this is distinct from the entity-level exclusion_status_flag / exclusion_url fields, which are a flag on an entity record, not the /exclusions/ resource.

Acceptance criteria

• 12 methods added to src/client.ts following existing naming (listDibbsRfqs, getDibbsRfq, listSbirTopics, listExclusions, …)
• Models / types for each resource, matching the shape schemas
• exclusion shape in explicitSchemas.ts wired to its new client methods
• Tests following the existing mock-driven pattern in tests/
• README + CHANGELOG updated