L-w3: complete three-accent pastel repalette + REAPER-grey neutrals

Finish roleColor/roleColorState for the three-accent enum, re-map every
Accent consumer (primary leads live; Pool/Banks titles categorical
secondary/tertiary), make spectralColor a lime->teal->purple three-stop
sweep, and re-lock the WCAG-floor tests on the grey ladder.

src/theme.h

@@ -2,16 +2,20 @@
 // theme — the REAPER-free, LICE-free palette + type-scale core of the shared drawing
 // kit (Phase L, L1). This is the "one source of drawing" made testable at its root: a
 // ROLE-based color model (bg/base, bg/panel, bg/cell, line/hairline, text/primary,
-// text/dim, accent, accent/hot, warn), an INTERACTION-STATE model (rest/hover/active/
-// pressed/dragging/focus/disabled), and the WCAG contrast math that lets a unit test
-// prove every text-on-surface pair clears its floor ("punch to the floor, not past it").
+// text/dim, accent/primary, accent/secondary, accent/tertiary, accent/hot, warn), an
+// INTERACTION-STATE model (rest/hover/active/pressed/dragging/focus/disabled), and the
+// WCAG contrast math that lets a unit test prove every text-on-surface pair clears its
+// floor ("punch to the floor, not past it").
 //
-// THE SINGLE POINT OF CHANGE (DS-2): every role color is produced by roleColor() from
-// ONE direction constants block (kDirection*, below) carrying the settled B (Neon
-// Console) + C spectral values. Switching the visual direction is editing that block and
-// nothing else — no shell hardcodes a color; the shell asks the theme by role. The
-// spectral (Direction C) hue ramp lives here too (spectralColor) so the signature
-// keyboard strip's L3 consumer derives its per-note hue from the same source.
+// THE SINGLE POINT OF CHANGE (DS-2 revised): every role color is produced by roleColor()
+// from ONE direction constants block (kDirection*, below) carrying the settled B (Neon
+// Console) neutrals — now REAPER-theme mid-grey, not near-black — plus the three-accent
+// pastel system (primary lime / secondary teal / tertiary purple) and the C pastel
+// spectral ramp. Switching the visual direction is editing that block and nothing else —
+// no shell hardcodes a color; the shell asks the theme by role. The spectral (Direction C)
+// hue ramp lives here too (spectralColor) so the signature keyboard strip's L3 consumer
+// derives its per-note hue from the same source (a pastel sweep anchored on the three
+// accents: primary lime -> secondary teal -> tertiary purple).
 //
 // PURE MODULE: NO REAPER types, NO SWELL, NO LICE, NO vendor/ includes. Standard library
 // only. Builds and unit-tests without REAPER. Mirror of mode_switch / bank_grid — the
@@ -40,15 +44,17 @@ struct KitColor {
 // The structural palette roles (direction-independent — §2.1 of the design doc). The
 // direction (B/C) sets the concrete hue behind each; the shell always asks by role.
 enum class Role {
-    BgBase,      // window canvas
-    BgPanel,     // a raised region (list, waveform pane)
-    BgCell,      // a control / row surface
-    LineHairline,// separators (used sparingly — elevation carries most separation)
-    TextPrimary, // labels, values
-    TextDim,     // secondary / units
-    Accent,      // selection / active / focus — where the punch lives
-    AccentHot,   // hover / live / drag feedback (a brighter accent tint)
-    Warn,        // clip / destructive (prune, delete) — reserved for byte-deleting states
+    BgBase,        // window canvas
+    BgPanel,       // a raised region (list, waveform pane)
+    BgCell,        // a control / row surface
+    LineHairline,  // separators (used sparingly — elevation carries most separation)
+    TextPrimary,   // labels, values
+    TextDim,       // secondary / units
+    AccentPrimary, // the live / active / selected signal — where the punch lives (pastel lime)
+    AccentSecondary,// categorical role A (pastel teal) — a distinct KIND, never intensity
+    AccentTertiary,// categorical role B (pastel purple) — a distinct KIND, never intensity
+    AccentHot,     // hover / live / drag feedback (a brighter tint OF the primary accent)
+    Warn,          // clip / destructive (prune, delete) — reserved for byte-deleting states
 };
 
 // The interaction-state model every kit component honors (§3.3). A component draws its
@@ -83,11 +89,15 @@ KitColor roleColor(Role role);
 // Rest returns roleColor(role) unchanged.
 KitColor roleColorState(Role role, InteractionState state);
 
-// Direction C's spectral hue ramp: maps a normalized position t in [0, 1] (low note ->
-// high note across the keyboard strip) to a color, cool-blue at 0 -> hot-magenta at 1
-// (§4 Direction C). The signature keyboard-strip surface (an L3 consumer) derives each
-// note/zone's hue from this ONE function so the spectrum is defined in the same place as
-// the rest of the palette. t is clamped to [0, 1].
+// Direction C's spectral hue ramp (DS-2 revised — a PASTEL sweep anchored on the three
+// accents, not the old neon cool-blue -> hot-magenta): maps a normalized position t in
+// [0, 1] (low note -> high note across the keyboard strip) to a color that runs
+// accent/primary (pastel lime, low) -> accent/secondary (pastel teal, mid) ->
+// accent/tertiary (pastel purple, high). The same three hues that mean "live / category A
+// / category B" elsewhere are the endpoints and midpoint here, so the strip reads as an
+// extension of the accent system, not a separate flourish. The signature keyboard-strip
+// surface (an L3 consumer) derives each note/zone's hue from this ONE function so the
+// spectrum is defined in the same place as the rest of the palette. t is clamped to [0, 1].
 KitColor spectralColor(double t);
 
 // --- WCAG contrast (the "punch" rule, made testable) --------------------------