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

@@ -21,7 +21,7 @@ Install colorsaver using your favorite package manager.
 
 ```lua
 {
-  "https://git.sr.ht/~swaits/colorsaver.nvim",
+  "https://git.swaits.com/swaits/colorsaver.nvim",
   lazy = true,
   event = "VimEnter",
   opts = { 
@@ -49,7 +49,7 @@ look like this:
 
     -- load/save our last used colorscheme automatically
     {
-      "https://git.sr.ht/~swaits/colorsaver.nvim",
+      "https://git.swaits.com/swaits/colorsaver.nvim",
       event = "VimEnter",
       opts = {},
       dependencies = {
@@ -68,7 +68,7 @@ look like this:
 
 ```lua
 {
-  "https://git.sr.ht/~swaits/colorsaver.nvim",
+  "https://git.swaits.com/swaits/colorsaver.nvim",
   config = function()
     require("colorsaver").setup({ 
       -- your options here
@@ -80,7 +80,7 @@ look like this:
 ### [vim-plug](https://github.com/junegunn/vim-plug)
 
 ```vim
-Plug 'https://git.sr.ht/~swaits/colorsaver.nvim'
+Plug 'https://git.swaits.com/swaits/colorsaver.nvim'
 lua require("colorsaver").setup({ 
     -- your options here
 })