fix(tui): bump Subtle ANSI fallback from "8" to "7"

Bright black ("8") plus Faint made PENDING status and dividers nearly
invisible in 16-color terminals. White ("7") with Faint renders as a
readable dim gray while still sitting below Muted in the hierarchy.

internal/tui/theme.go

@@ -60,7 +60,7 @@ var themeFlexokiDark = Theme{
 	Border:     cc("#575653", "8"),
 	Fg:         cc("#CECDC3", "15"),
 	Muted:      cc("#878580", "7"),
-	Subtle:     cc("#6F6E69", "8"),
+	Subtle:     cc("#6F6E69", "7"),
 	Success:    cc("#879A39", "10"),
 	Warning:    cc("#D0A215", "11"),
 	Stale:      cc("#DA702C", "3"),
@@ -81,7 +81,7 @@ var themeTokyoNight = Theme{
 	Border:     cc("#3b4261", "8"),
 	Fg:         cc("#c0caf5", "15"),
 	Muted:      cc("#a9b1d6", "7"),
-	Subtle:     cc("#565f89", "8"),
+	Subtle:     cc("#565f89", "7"),
 	Success:    cc("#9ece6a", "10"),
 	Warning:    cc("#e0af68", "11"),
 	Stale:      cc("#ff9e64", "3"),
@@ -102,7 +102,7 @@ var themeGruvbox = Theme{
 	Border:     cc("#665c54", "8"),
 	Fg:         cc("#ebdbb2", "15"),
 	Muted:      cc("#bdae93", "7"),
-	Subtle:     cc("#7c6f64", "8"),
+	Subtle:     cc("#7c6f64", "7"),
 	Success:    cc("#b8bb26", "10"),
 	Warning:    cc("#fabd2f", "11"),
 	Stale:      cc("#fe8019", "3"),
@@ -123,7 +123,7 @@ var themeCatppuccinMocha = Theme{
 	Border:     cc("#585b70", "8"),
 	Fg:         cc("#cdd6f4", "15"),
 	Muted:      cc("#a6adc8", "7"),
-	Subtle:     cc("#6c7086", "8"),
+	Subtle:     cc("#6c7086", "7"),
 	Success:    cc("#a6e3a1", "10"),
 	Warning:    cc("#f9e2af", "11"),
 	Stale:      cc("#fab387", "3"),
@@ -144,7 +144,7 @@ var themeNord = Theme{
 	Border:     cc("#4c566a", "8"),
 	Fg:         cc("#d8dee9", "15"),
 	Muted:      cc("#d8dee9", "7"),
-	Subtle:     cc("#4c566a", "8"),
+	Subtle:     cc("#4c566a", "7"),
 	Success:    cc("#a3be8c", "10"),
 	Warning:    cc("#ebcb8b", "11"),
 	Stale:      cc("#d08770", "3"),