chore: repoint remaining links at git.swaits.com

Rewrites lingering github.com / *.sr.ht references to this Gitea instance,
translating GitHub and Sourcehut URL shapes to Gitea's (/blob/<ref>/ and
sr.ht /tree/<ref>/item/ -> /src/branch/<ref>/, /tree/<tag> -> /src/tag/<tag>,
/actions/workflows/X -> /actions?workflow=X, /edit/ -> /_edit/).

Left pointing at the old hosts on purpose: pull-request links (PRs were not
migrated), forks that were never migrated, and GitHub-only surfaces Gitea
lacks. OpenPGP identity proofs are untouched by design.

versions/v0.1.0/01-wire-format.md

@@ -131,7 +131,7 @@ A conforming decoder MUST reject packets with any of the following:
 
 - [Section 2: Header](02-header.md) — Header byte encoding details
 - [Section 3: Path](03-path.md) — Path length encoding and path field
-- Test vectors: [`corpus/wire-format/framing/`](https://github.com/swaits/meshcore-spec/tree/main/versions/v0.1.0/corpus/wire-format/framing/), [`corpus/wire-format/invalid/`](https://github.com/swaits/meshcore-spec/tree/main/versions/v0.1.0/corpus/wire-format/invalid/)
+- Test vectors: [`corpus/wire-format/framing/`](https://git.swaits.com/swaits/meshcore-spec/src/branch/main/versions/v0.1.0/corpus/wire-format/framing/), [`corpus/wire-format/invalid/`](https://git.swaits.com/swaits/meshcore-spec/src/branch/main/versions/v0.1.0/corpus/wire-format/invalid/)
 
 ### Reference Implementation