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/ui/panes/highlight.go

@@ -9,7 +9,6 @@ import (
 	"github.com/charmbracelet/x/ansi"
 )
 
-// sgr matches SGR escape sequences.
 var sgr = regexp.MustCompile("\x1b\\[([0-9;:]*)m")
 
 // Highlight draws a cursor row: line, padded to width, on style's