feat(webhook-api): add optional source to quote/swap requests and responses

[ioanSL]

Summary

Adds an optional source field to the market-maker webhook contract in webhook-api so MMs can see where traffic originates: "internal" (a Jupiter product) or "integrator" (a third-party integrator).

• requests::QuoteRequest and requests::SwapRequest: set by the RFQ API.
• responses::QuoteResponse and responses::SwapResponse: echo of the request value.
• server-example echoes it; one serde test covers the field missing and present.

The field is Option<String> and omitted when None, so MMs that upgrade this crate before the RFQ API rolls out keep deserializing today's requests, and MMs on older versions ignore the new key.

Not included: openapi/openapi.json is not regenerated here, since it is already behind (isWsol, receiver are missing) and deserves its own refresh.

Follow-up in jup-ag/rfq: bump the webhook-api rev to this commit and populate source from the authenticated request source, overwriting any taker-supplied value on /v1/execute.

Audit Status

• Required — Audit completed and artifacts attached
• Not Required — Justification below

If Not Required (Justification)

Off-chain Rust API types only (webhook-api and server-example). No on-chain program, order-engine-sdk or squads-sdk change. The change is an additive optional serde field with no validation or funds-flow logic; existing integrations are unaffected because the field is Option and skipped when None.

Deployment Intent

• No deploy
• Deploy new program
• Upgrade existing program

🤖 Generated with Claude Code

[github-actions]

Coverage report

Filename	Lines Covered (%)	Functions Covered (%)
order-engine-sdk/src/fill.rs	96.24	89.19
order-engine-sdk/src/lib.rs	0	0
order-engine-sdk/src/transaction.rs	0	0
programs/order-engine/src/error.rs	100	100
programs/order-engine/src/instructions/fill.rs	98.29	80
programs/order-engine/src/lib.rs	90.91	75
server-example/src/config.rs	0	0
server-example/src/server.rs	0	0
squads-sdk/src/accounts.rs	93.51	100
squads-sdk/src/config.rs	39.68	50
squads-sdk/src/error.rs	0	0
squads-sdk/src/lib.rs	100	100
squads-sdk/src/pda.rs	98.04	100
squads-sdk/src/serialize.rs	70.83	60
squads-sdk/src/settings.rs	94.02	100
squads-sdk/src/transaction.rs	44.33	44.44
squads-sdk/src/unwrap.rs	89.43	71.43
squads-sdk/src/wrap.rs	84.28	85.71
webhook-api/src/enums.rs	88.75	18.18
webhook-api/src/requests.rs	81.82	33.33
webhook-api/src/responses.rs	0	0