feat(themes): apply color themes in regular (non-powerline) mode (fg-only) - #12

What

Makes the built-in theme catalog usable in regular (non-powerline) mode: a new top-level theme setting cycles the chosen theme's segment palette across widgets as foreground colors. Feature half of sirmalloc#604 (the U+E0B0 separator fallback is deliberately left for a separate change).

Semantics

• theme: "dracula" (any POWERLINE_THEMES name) cycles theme[level].bg[] as widget foregrounds — bg[] is the vivid segment palette, while fg[] holds the dark text colors meant to sit on those segments. ansi16-level bg* names are converted through the existing bgToFg() helper.
• Explicit per-widget colors win over the theme; the theme beats widget default colors. Explicit colors keep their palette slot, so adding one accent doesn't shift the rhythm of the surrounding widgets.
• Separators and flex separators are not themed and consume no slot (powerline filters them out before indexing — same rule).
• Merged widgets share one slot; preserves-colors widgets keep their intrinsic ANSI output and still advance the slot — both mirror the powerline renderer.
• Unset / 'custom' / unknown name → no theming. The level follows colorLevel, using the 16/256/truecolor calibrations already shipped with each theme.
• Additive optional schema key: old configs parse unchanged, no version bump. ccstatusline set theme <name> / get work through the existing generic allowlist — zero CLI code changes. A TUI picker is left to the maintainer; this PR is config+CLI only.

Verification

• bun test: 2450 pass / 0 fail. New renderer-regular-theme.test.ts covers cycle order, explicit-wins + slot rhythm, separators unthemed, preserves-colors, merged widgets sharing a slot, unset/'custom'/unknown names, level 1/2/3 (including the bgToFg conversion for ansi16 palettes), and schema round-trip.
• bun run lint clean; bun run build OK.
• Render check through the built binary with a theme: "dracula", colorLevel: 3 config: uncolored widgets emit exact truecolor codes (38;2;189;147;249, 38;2;248;248;242, …), separators stay unthemed.
• CLI round-trip: set theme nord → get --json reports "theme":"nord".
• Live run as the active Claude Code status line (theme set, per-widget colors temporarily removed): all widgets picked up the cycled Dracula palette in the real render path; config restored afterwards.

🤖 Generated with Claude Code