Integrate impeccable design quality tools

Selective integration from pbakaus/impeccable (Apache 2.0):

Reference material (docs/reference/impeccable/):
- 7 design guides: typography, color-and-contrast, spatial-design,
  motion-design, interaction-design, responsive-design, ux-writing
- 3 critique references: cognitive-load, heuristics-scoring, personas
- 4 skill references for internal use: audit, critique, polish,
  frontend-design (anti-patterns list)

New skills:
- /audit — technical quality scoring (0-20) across 5 dimensions:
  accessibility, performance, theming, responsive, design quality
- /critique — UX design review using Nielsen's 10 heuristics (0-40),
  adapted for FA's sensitive audience context

Updated skills:
- /review-component — added interactive states checklist and design
  anti-patterns checklist (8 checks each)
- /preflight — added visual QA spot-check section (transitions,
  focus-visible, touch targets, spacing consistency)

No code changes — all existing components, tokens, and theme untouched.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/reference/impeccable/color-and-contrast.md

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+# Color & Contrast
+
+## Color Spaces: Use OKLCH
+
+**Stop using HSL.** Use OKLCH (or LCH) instead. It's perceptually uniform, meaning equal steps in lightness *look* equal—unlike HSL where 50% lightness in yellow looks bright while 50% in blue looks dark.
+
+```css
+/* OKLCH: lightness (0-100%), chroma (0-0.4+), hue (0-360) */
+--color-primary: oklch(60% 0.15 250);      /* Blue */
+--color-primary-light: oklch(85% 0.08 250); /* Same hue, lighter */
+--color-primary-dark: oklch(35% 0.12 250);  /* Same hue, darker */
+```
+
+**Key insight**: As you move toward white or black, reduce chroma (saturation). High chroma at extreme lightness looks garish. A light blue at 85% lightness needs ~0.08 chroma, not the 0.15 of your base color.
+
+## Building Functional Palettes
+
+### The Tinted Neutral Trap
+
+**Pure gray is dead.** Add a subtle hint of your brand hue to all neutrals:
+
+```css
+/* Dead grays */
+--gray-100: oklch(95% 0 0);     /* No personality */
+--gray-900: oklch(15% 0 0);
+
+/* Warm-tinted grays (add brand warmth) */
+--gray-100: oklch(95% 0.01 60);  /* Hint of warmth */
+--gray-900: oklch(15% 0.01 60);
+
+/* Cool-tinted grays (tech, professional) */
+--gray-100: oklch(95% 0.01 250); /* Hint of blue */
+--gray-900: oklch(15% 0.01 250);
+```
+
+The chroma is tiny (0.01) but perceptible. It creates subconscious cohesion between your brand color and your UI.
+
+### Palette Structure
+
+A complete system needs:
+
+| Role | Purpose | Example |
+|------|---------|---------|
+| **Primary** | Brand, CTAs, key actions | 1 color, 3-5 shades |
+| **Neutral** | Text, backgrounds, borders | 9-11 shade scale |
+| **Semantic** | Success, error, warning, info | 4 colors, 2-3 shades each |
+| **Surface** | Cards, modals, overlays | 2-3 elevation levels |
+
+**Skip secondary/tertiary unless you need them.** Most apps work fine with one accent color. Adding more creates decision fatigue and visual noise.
+
+### The 60-30-10 Rule (Applied Correctly)
+
+This rule is about **visual weight**, not pixel count:
+
+- **60%**: Neutral backgrounds, white space, base surfaces
+- **30%**: Secondary colors—text, borders, inactive states
+- **10%**: Accent—CTAs, highlights, focus states
+
+The common mistake: using the accent color everywhere because it's "the brand color." Accent colors work *because* they're rare. Overuse kills their power.
+
+## Contrast & Accessibility
+
+### WCAG Requirements
+
+| Content Type | AA Minimum | AAA Target |
+|--------------|------------|------------|
+| Body text | 4.5:1 | 7:1 |
+| Large text (18px+ or 14px bold) | 3:1 | 4.5:1 |
+| UI components, icons | 3:1 | 4.5:1 |
+| Non-essential decorations | None | None |
+
+**The gotcha**: Placeholder text still needs 4.5:1. That light gray placeholder you see everywhere? Usually fails WCAG.
+
+### Dangerous Color Combinations
+
+These commonly fail contrast or cause readability issues:
+
+- Light gray text on white (the #1 accessibility fail)
+- **Gray text on any colored background**—gray looks washed out and dead on color. Use a darker shade of the background color, or transparency
+- Red text on green background (or vice versa)—8% of men can't distinguish these
+- Blue text on red background (vibrates visually)
+- Yellow text on white (almost always fails)
+- Thin light text on images (unpredictable contrast)
+
+### Never Use Pure Gray or Pure Black
+
+Pure gray (`oklch(50% 0 0)`) and pure black (`#000`) don't exist in nature—real shadows and surfaces always have a color cast. Even a chroma of 0.005-0.01 is enough to feel natural without being obviously tinted. (See tinted neutrals example above.)
+
+### Testing
+
+Don't trust your eyes. Use tools:
+
+- [WebAIM Contrast Checker](https://webaim.org/resources/contrastchecker/)
+- Browser DevTools → Rendering → Emulate vision deficiencies
+- [Polypane](https://polypane.app/) for real-time testing
+
+## Theming: Light & Dark Mode
+
+### Dark Mode Is Not Inverted Light Mode
+
+You can't just swap colors. Dark mode requires different design decisions:
+
+| Light Mode | Dark Mode |
+|------------|-----------|
+| Shadows for depth | Lighter surfaces for depth (no shadows) |
+| Dark text on light | Light text on dark (reduce font weight) |
+| Vibrant accents | Desaturate accents slightly |
+| White backgrounds | Never pure black—use dark gray (oklch 12-18%) |
+
+```css
+/* Dark mode depth via surface color, not shadow */
+:root[data-theme="dark"] {
+  --surface-1: oklch(15% 0.01 250);
+  --surface-2: oklch(20% 0.01 250);  /* "Higher" = lighter */
+  --surface-3: oklch(25% 0.01 250);
+
+  /* Reduce text weight slightly */
+  --body-weight: 350;  /* Instead of 400 */
+}
+```
+
+### Token Hierarchy
+
+Use two layers: primitive tokens (`--blue-500`) and semantic tokens (`--color-primary: var(--blue-500)`). For dark mode, only redefine the semantic layer—primitives stay the same.
+
+## Alpha Is A Design Smell
+
+Heavy use of transparency (rgba, hsla) usually means an incomplete palette. Alpha creates unpredictable contrast, performance overhead, and inconsistency. Define explicit overlay colors for each context instead. Exception: focus rings and interactive states where see-through is needed.
+
+---
+
+**Avoid**: Relying on color alone to convey information. Creating palettes without clear roles for each color. Using pure black (#000) for large areas. Skipping color blindness testing (8% of men affected).