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/linkhandler/install_darwin.go

@@ -114,7 +114,7 @@ func Check() string {
 	}
 	out, err := exec.Command("plutil", "-extract", exeKey, "raw", filepath.Join(app, "Contents", "Info.plist")).Output()
 	if err != nil {
-		return "" // installed before the key was recorded: assume it works
+		return "" // can't tell: assume it works
 	}
 	if exe := strings.TrimSpace(string(out)); !exists(exe) {
 		return "lazysecrets:// links run " + exe + ", which no longer exists"