release: Qualify built packages with stable Core v32 #207

Split from #52 so package-artifact qualification can merge without waiting for stable Bitcoin Core binaries. This remains a prerequisite for production v1 publication.

Once official stable v32 binaries and checksums are available:

• Complete core: Pin fixtures and tutorials to stable v32.0 #164's stable fixture pin: verify the official archive against its published checksum and record the upstream version and digest.
• Add one release job that installs release: Qualify packages before publishing #52's already-built wheel in an isolated environment and runs tools/bitcoin_core_regtest.py with those stable binaries. Ensure imports come from the installed wheel, not the checkout.
• Require that job before PyPI/GitHub publication and retain the Core version with the package hashes and source commit.
• Replace release: Qualify packages before publishing #52's temporary prerelease-only publication condition with that required Core job; stable-version tags currently build/test packages but cannot publish them. Verify the failure path blocks publication.
• Qualify the frozen v1 candidate through that path and record the result under Gate v1 publication on package and stable-Core qualification #5 before production publication.

Reuse #164 for the fixture/tutorial version change; this issue owns the release-job dependency and exact-built-package integration. Do not add another source-test/static-analysis matrix already covered by normal CI. The existing pypi environment currently has no approval protection rules, so the temporary publication condition is necessary; naming an environment alone is not an approval gate.

Current observation: the signed v32.0 source tag exists, but the official binary directory lists release candidates. Recheck availability before implementation rather than assuming a source tag means stable binaries are published.