docs: CCTP native-USDC deposit integration guide

[evchip]

Problem

Integration partners (Injective is in flight) need public documentation for funding Amplifi accounts with native USDC via CCTP. The flow shipped today in the main repo (amplifi#1597, amplifi#1598) and was verified end-to-end on production, but nothing in the docs describes it.

What changed

New Integrations section with one page, "Deposit via CCTP (Native USDC)":

• The 5-step partner flow (provision wallet → CCTP burn → relay mint → confirm with the mint tx hash → poll balance until credited), using the stable app.amplifi.finance/api base URL.
• The confirm endpoint's error contract (4xx permanent / 5xx transient / idempotent re-confirms) and the forwarding: true response semantics.
• Constraints: $2 minimum per deposit, ~30–60s credit latency after the Polygon mint, withdrawals pay out USDC.e on Polygon.

Numbers and semantics match the live production behavior verified today (deposit credited hands-free ~40s after mint).

User prompts

(After the live CCTP e2e run passed end-to-end on production and the user prepared to share the reference script with the partner:)

i am going to share this script with injective just to show them how the integration would work. just bare min to show it works. [pasted passing run + backend logs] why is this taking 40 seconds? … anything else to add to the script? can we update the docs? @../../../../amplifi-docs/

🤖 Generated with Claude Code

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Note

Low Risk
Documentation-only changes with no runtime, auth, or data-path impact.

Overview
Adds a new Integrations section to the docs site and publishes Deposit via CCTP (Native USDC) for partners funding Amplifi with native USDC over Circle CCTP.

The page documents the five-step flow against app.amplifi.finance/api: provision deposit wallet, burn on source chain (Fast vs standard CCTP settings), relay mint on Polygon, confirm with the Polygon mint tx hash, then poll balance until credited. It also covers the confirm endpoint’s 2xx / 4xx / 5xx behavior and idempotent re-confirms, forwarding: true semantics, and operational constraints ($2 minimum, ~30–60s credit after mint, withdrawals as USDC.e on Polygon).

Navigation is wired via content/docs/meta.json and content/docs/integrations/meta.json.

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