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

cliff.toml

@@ -49,6 +49,8 @@ commit_preprocessors = [
   # A merge commit (not a squash) says "Merge pull request 'feat: …' (#4)
   # from branch into main": keep the title and number.
   { pattern = "^Merge pull request '(.+)' \\((#[0-9]+)\\) from .*", replace = "${1} (${2})" },
+  # #11 was squash-merged with #10 (the status pane) in it: name both.
+  { pattern = "^feat: link each changelog entry to its PR and commit \\(#11\\)", replace = "feat: a status pane (0) with version, updates, accounts, files and links; changelog entries link to their PR and commit (#11)" },
   # Titles may be written "[feat] x", "[feat]: x" or "feat:x" (see
   # pr-title.yml); all become "feat: x".
   { pattern = "^\\[(feat|fix|perf|refactor|docs|test|ci|chore|build|style|revert)(\\([^)]*\\))?(!?)\\](!?):?\\s*", replace = "${1}${2}${3}${4}: " },