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.

README.md

@@ -59,7 +59,7 @@ first. Don't "clean them up" — they're the docs.
 With `vim.pack` (Neovim 0.12+):
 
 ```lua
-vim.pack.add({ 'https://github.com/swaits/tiny-jump.nvim' })
+vim.pack.add({ 'https://git.swaits.com/swaits/tiny-jump.nvim' })
 
 vim.keymap.set({ 'n', 'x', 'o' }, 's', require('tiny-jump').start)
 ```