Initial CBTC BTC Implementation

[Fletch153]

Closes #DS-990

Description

Adds a new CBTC Bitcoin Proof of Reserves adapter that queries Bitcoin blockchain UTXOs directly to verify BTC reserves across configured vault addresses.

Changes

• Add new @chainlink/dlc-cbtc-btc-por-adapter package
• Implement Bitcoin UTXO querying via Electrs-compatible API
• Add confirmation threshold check (configurable, default 6 blocks)
• Implement iBTC-style pending withdrawal handling to prevent temporary reserve dips during unconfirmed spends
• Add unit tests for reserve calculation logic
• Add integration tests with mocked Bitcoin API responses

Steps to Test

1. Build the adapter:

   cd packages/sources/dlc-cbtc-btc-por && yarn build

2. Run unit tests:

   yarn jest packages/sources/dlc-cbtc-btc-por/test/unit/reserves.test.ts --no-coverage

3. Start the adapter locally:

   BITCOIN_RPC_ENDPOINT="https://mainnet.dlc.link/electrs" \
   VAULT_ADDRESSES="bc1pckcdqraqg7gy83w4ddvvc3hks8wvcjvldw2kchlvyre5v9fw37jqse4kn0,bc1p90eyryydrg2w3pswwp0qa2p9elgp09jte34ykxqn0uk6g7dnzqks9n3342" \
   EA_PORT=8080 \
   yarn start

4. Query the reserves endpoint:

   curl -X POST http://localhost:8080 -H "Content-Type: application/json" -d '{"endpoint": "reserves"}'

5. Verify the response returns total reserves in satoshis:

   {
     "result": 301089400,
     "data": { "result": 301089400 },
     "statusCode": 200
   }

Quality Assurance

• If a new adapter was made, or an existing one was modified so that its environment variables have changed, update the relevant infra-k8s configuration file.

• If a new adapter was made, or an existing one was modified so that its environment variables have changed, update the relevant adapter-secrets configuration file.

• If a new adapter was made, or a new endpoint was added, update the test-payload.json file with relevant requests.

• The branch naming follows git flow (feature/x, chore/x, release/x, hotfix/x, fix/x) or is created from Jira.

• This is related to a maximum of one Jira story or GitHub issue.

• Types are safe (avoid TypeScript/TSLint features like any and disable, instead use more specific types).

• All code changes have 100% unit and integration test coverage. If testing is not applicable or too difficult to justify doing, the reasoning should be documented explicitly in the PR.

[changeset-bot]

🦋 Changeset detected

Latest commit: 2cf4156

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@chainlink/dlc-cbtc-por-adapter	Major

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[mmcallister-cll]

This doesn't look like the correct structure. We don't have instances of nested EAs under a since source EA. You might want to consider separating these out into multiple packages/sources EAs for discrete APIs and/or packages/composites for EAs that call other EAs.