Fix help text, add missing descriptions for pipx/mas, add 3 built-in themes

[Copilot]

Four top-priority gaps identified in the repo: stale CLI help listing only 13 of 36 managers, two managers with no description support (pipx, mas), and three themes listed in the roadmap but never shipped.

Changes

cmd/gpk/main.go — help text

Updated Supported managers: to list all 36 managers accurately.

internal/manager/pipx.go — add Describe()

Reads Summary from each tool's .dist-info/METADATA inside its pipx venv — same offline approach as uv.go. Respects PIPX_HOME env var.

func pipxLocalSummary(venvsDir, name string) string {
    pattern := filepath.Join(venvsDir, name, "lib", "python*", "site-packages", normalized+"-*.dist-info", "METADATA")
    // falls back to non-normalized name if no match
    return parseMetadataSummary(matches[0])
}

internal/manager/mas.go — add Describe()

Scan() now stores the numeric App Store ID in Package.Location. Describe() fans out concurrent iTunes lookup API calls (https://itunes.apple.com/lookup?id=<id>, max 5 goroutines) and trims descriptions to the first line, capped at 200 chars.

internal/config/themes/ — missing built-in themes

Added solarized-dark.toml, one-dark.toml, and rose-pine.toml — all three were listed in ROADMAP.md but absent from the themes directory.

tests/parsing/pipx_mas_describe_test.go

New tests covering METADATA Summary extraction, iTunes JSON response parsing, empty-result handling, and the updated mas.Scan() ID-capture logic.

[programmersd21]

@neur0map pls check it. lgtm :D