chore: migrate git host from git.dev.rkdr.net to git.rkdr.net

Why
The repo's git host moved from git.dev.rkdr.net to git.rkdr.net. The
`origin` remote was already repointed; this commit brings every
in-repo reference in line so cloning, submodule init, and apm install
all resolve against the new host.

Implementation Notes
- .gitmodules: docs/wiki submodule URL repointed (tests/* submodules
  stay on github.com, untouched).
- Root apm.yml: 7 dependency entries and marketplace.owner.url
  repointed; executables.allow key updated to kyberforge#2.0.1 to
  match kyberforge's bump below (scripts/check-executables-allow-sync.sh
  enforces this pairing).
- Each plugin's apm.yml (bin, core, git, gitea, kyberforge, lint,
  onedev): author.url/homepage/repository repointed. Per this repo's
  apm versioning policy, these fields compile verbatim into
  plugin.json, so each package took a patch version bump alongside
  the URL change.
- Root apm.yml version and marketplace.version bumped 0.5.0 -> 0.5.1
  to match (a marketplace-block field and every listed package's
  version moved).
- apm.lock.yaml regenerated via `apm install`; .claude-plugin/marketplace.json
  regenerated via `apm pack --marketplace=claude` so compiled output
  stays in sync with the manifests.

Impact
docs/adr/0015, 0017, and 0018 intentionally keep the old host in their
issue links and examples — they are historical decision records, not
live config. Verified clean: apm pack --check-clean, apm audit --ci,
check-executables-allow-sync.sh, and pre-commit --all-files all pass.

.gitmodules

@@ -12,4 +12,4 @@
 	ignore = dirty
 [submodule "docs/wiki"]
 	path = docs/wiki
-	url = git@git.dev.rkdr.net:Defame1297/holocron.wiki.git
+	url = git@git.rkdr.net:Defame1297/holocron.wiki.git