libsecp256k1

This change only edits the project's automated continuous-integration (CI) configuration file. It turns on all optional cryptographic modules by default in CI and adds test runs that disable each module one at a time. There is no change to the actual library source code, build scripts, or released binaries, so it cannot directly introduce a runtime security vulnerability or fix one in shipped code. It is a testing-infrastructure cleanup that also increases coverage of build configurations.

This commit only makes minor wording edits to the project's release-process documentation. It changes a few phrases from 'PR is merged' to 'PR has been merged', adds 'a' before 'PR', and adds a new step reminding maintainers to merge release notes before announcing a release. There is no code change and no security relevance.

This commit is a simple reorganization of the project's release-process documentation. It renames some sections, splits steps into clearer subsections, and adds minor wording clarifications (for example, reminding maintainers to manually review commits since the last release when writing changelog entries). No code, build scripts, cryptographic logic, or configuration defaults were changed.

This change fixes a small but real flaw in the MuSig test code. Previously, two test helper functions called internal loading/summing routines and then checked whether the results were the special 'point at infinity' value. Because the input buffers were already initialized to infinity, a failed load or sum could still make the infinity checks pass, so the test would not actually detect a broken implementation. The patch adds explicit success checks so the test fails if those routines return an error. This only affects test code, not the cryptographic library used by real Bitcoin transactions, so it does not create a direct security vulnerability in production software.

This is a tiny test-only change. It makes one unit test compare the full 66-byte MuSig aggregate nonce output instead of only the first 33 bytes. It does not change any production code, cryptographic behavior, or library API.

This commit removes an unused internal helper function for serializing public keys and updates the test code to use two newer, more specific helper functions instead. There is no indication of a security bug being fixed; it appears to be a routine code cleanup.