feat: the changelog in the status pane, built in (#12)

The status pane's rows (`0`, then `enter`) end with the changelog: every release up to the running one, newest first.

```
v0.2.0     2026-10-12
           added: Search with fzf's scoring and query syntax (#11) (65dc2d7)
           fixed: …
v0.1.0     2026-10-10
           Hello world 👋
```

- `CHANGELOG.md` is embedded at build time by a small root package (`changelog.go`, `package lazysecrets`, `//go:embed`), so it needs no network and matches the binary. `release.sh` updates the file before tagging, so a release's binary includes its own entry. `go install …@latest` gets it too, since the module includes the file.
- Entries show as text: links become `(#11) (65dc2d7)` (`update.PlainLinks`, shared with the `U` notes). `/` filters them like any Fields pane (`/fixed`, `/search`), and `y` copies one.
- `cliff.toml`: #11 was squash-merged with #10 (the status pane) in it, so a preprocessor rewrites its entry to name both. Otherwise the status pane would be missing from the changelog.

Test for the parsing: versions and dates, kinds, links as text, a release's own words, and the header and footer left out.

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

---------

Co-authored-by: Karl-Einar Bergstrøm <karl-einarb@outlook.com>
Reviewed-on: #12

internal/ui/app/status_test.go

@@ -0,0 +1,30 @@
+package app
+
+import (
+	"testing"
+
+	"git.kebcloud.no/keb/lazysecrets/internal/ui/panes"
+)
+
+func TestChangelogFields(t *testing.T) {
+	t.Parallel()
+	md := "# Changelog\n\nEvery release of lazysecrets, newest first.\n\n## v0.2.0 – 2026-10-12\n\n### Added\n\n" +
+		"- Search ([#11](https://x/pulls/11)) ([65dc2d7](https://x/commit/65dc2d7))\n\n### Fixed\n\n- A fix (#3)\n\n" +
+		"## v0.1.0 – 2026-10-10\n\nHello world 👋\n\n<!-- generated by git-cliff (cliff.toml) -->\n"
+	got := changelogFields(md)
+	want := []panes.Field{
+		{Label: "v0.2.0", Value: "2026-10-12", Info: true},
+		{Value: "added: Search (#11) (65dc2d7)"},
+		{Value: "fixed: A fix (#3)"},
+		{Label: "v0.1.0", Value: "2026-10-10", Info: true},
+		{Value: "Hello world 👋"},
+	}
+	if len(got) != len(want) {
+		t.Fatalf("got %+v", got)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Errorf("row %d: %+v, want %+v", i, got[i], want[i])
+		}
+	}
+}