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/v0.1.0/16-packet-hash.md

@@ -59,7 +59,7 @@ function calculatePacketHash(packet):
 ### Cross-References
 
 - [Section 10: Trace](10-payload-trace.md) — TRACE packet special handling
-- Test vectors: [`corpus/crypto/sha256/packet-hash.json`](https://github.com/swaits/meshcore-spec/blob/main/versions/v0.1.0/corpus/crypto/sha256/packet-hash.json)
+- Test vectors: [`corpus/crypto/sha256/packet-hash.json`](https://git.swaits.com/swaits/meshcore-spec/src/branch/main/versions/v0.1.0/corpus/crypto/sha256/packet-hash.json)
 
 ### Reference Implementation