chore: tidy comments that repeat the code or no longer match it

- Comments that only restate a name (sgr, fg, mdLink, the repo provider's starred and current-repo notes) are gone.
- Stale ones match the code again: the repo package covers plain env files too, Launch runs argv, closeVersions no longer claims to move the cursor, and Check's fallback says why rather than naming a state no release had.
- The doc for versionString was attached to pseudo; the backtick in SourcesView's doc was a string-concatenation leftover; openFailed's doc was garbled.
- recentReleases sits next to latest, its user.
- .gitignore drops the Go template's boilerplate and patterns for files this project doesn't make.

internal/update/update.go

@@ -89,14 +89,9 @@ func (r Release) Notes(current string) string {
 	return PlainLinks(strings.TrimSpace(notes))
 }
 
-// recentReleases is how many releases Latest reads the changelogs of.
-const recentReleases = 10
-
 // PlainLinks shows Markdown links as their text, for a terminal.
 func PlainLinks(s string) string { return mdLink.ReplaceAllString(s, "$1") }
 
-// mdLink is a Markdown link, [text](url): the notes link PRs and commits,
-// and a terminal shows them as their text.
 var mdLink = regexp.MustCompile(`\[([^\]]+)\]\((https?://[^)\s]+)\)`)
 
 // Client talks to the release servers.
@@ -148,6 +143,9 @@ func (c *Client) Latest(ctx context.Context) (Release, error) {
 	return Release{}, errors.Join(errs...)
 }
 
+// recentReleases is how many releases Latest reads the changelogs of.
+const recentReleases = 10
+
 func (c *Client) latest(ctx context.Context, repo string) (Release, error) {
 	api, err := API(repo)
 	if err != nil {