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

cliff.toml

@@ -24,7 +24,8 @@ Hello world 👋
 {% for group, commits in commits | group_by(attribute="group") %}
 ### {{ group | striptags | trim }}
 {% for commit in commits %}
-- {% if commit.breaking %}**Breaking:** {% endif %}{{ commit.message | split(pat="\n") | first | upper_first | trim }}\
+- {% if commit.breaking %}**Breaking:** {% endif %}{{ commit.message | split(pat="\n") | first | upper_first | trim }} \
+([{{ commit.id | truncate(length=7, end="") }}](https://git.kebcloud.no/keb/lazysecrets/commit/{{ commit.id }}))\
 {% endfor %}
 {% endfor %}\n
 """
@@ -33,6 +34,8 @@ trim = true
 # Runs on each part (header, every release) separately.
 postprocessors = [
   { pattern = "\n{3,}", replace = "\n\n" },
+  # Squash commits end in the PR's number: link it.
+  { pattern = "\\(#([0-9]+)\\)", replace = "([#${1}](https://git.kebcloud.no/keb/lazysecrets/pulls/${1}))" },
 ]
 
 [git]