feat: link each changelog entry to its PR and commit (#11)

Like Immich's and RomM's release notes: every changelog entry now links to its pull request and its commit, in `CHANGELOG.md` and in the release notes on Gitea:

```
- Search with fzf's scoring and query syntax ([#11](…/pulls/11)) ([65dc2d7](…/commit/65dc2d7…))
```

- `cliff.toml`: the entry template adds the short commit hash as a link; a postprocessor turns the squash commit's `(#N)` into a link to the PR.
- The app shows release notes as text (`U`, and the status pane's changelog to come), so `Release.Notes()` turns Markdown links back into their text: `Search (#11) (65dc2d7)`.

Checked with `git cliff --unreleased` on main: every entry since v0.1.0 gets both links. Test for the link stripping.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Karl-Einar Bergstrøm <karl-einarb@outlook.com>
Reviewed-on: #11

internal/ui/app/layout_test.go

@@ -258,14 +258,13 @@ func TestNoHighlightWhileTerminalBlurred(t *testing.T) {
 	}
 }
 
-func TestVersionBottomRight(t *testing.T) {
+func TestVersionInStatus(t *testing.T) {
 	t.Parallel()
 	d := newDriverOpts(t, Options{Version: "0.1.0"})
-	bar := lastLine(d.screen())
-	if !strings.HasSuffix(bar, "v0.1.0 ") || ansi.StringWidth(bar) != 100 {
-		t.Errorf("help line %q (%d wide)", bar, ansi.StringWidth(bar))
+	if !strings.Contains(d.screen(), "[0] lazysecrets v0.1.0") {
+		t.Errorf("no version in the status pane:\n%s", d.screen())
 	}
-	if !strings.Contains(bar, "? help • q quit") {
-		t.Errorf("help squeezed out by the version: %q", bar)
+	if bar := lastLine(d.screen()); strings.Contains(bar, "v0.1.0") || !strings.Contains(bar, "? help • q quit") {
+		t.Errorf("help line %q", bar)
 	}
 }