chore: repoint URLs at git.swaits.com and bump for release

Rewrites remaining github.com / git.sr.ht references to git.swaits.com,
translating GitHub URL shapes to Gitea's (/blob/<ref>/ -> /src/branch/<ref>/,
/tree/<tag> -> /src/tag/<tag>, /actions/workflows/X -> /actions?workflow=X,
/edit/ -> /_edit/).

Left pointing at GitHub on purpose: pull-request links (PRs were not migrated)
and GitHub-only surfaces Gitea lacks (security advisories, discussions).

Cargo.toml

@@ -1,11 +1,11 @@
 [package]
 name = "ringa"
-version = "0.1.2"
+version = "0.1.3"
 edition = "2021"
 license = "MIT"
 description = "GPU-rendered ring light overlay for Wayland"
 repository = "https://git.swaits.com/swaits/ringa"
-homepage = "https://github.com/swaits/ringa"
+homepage = "https://git.swaits.com/swaits/ringa"
 readme = "README.md"
 keywords = ["wayland", "ring-light", "overlay", "wgpu", "camera"]
 categories = ["command-line-utilities", "multimedia"]