design: purple is dead — zero banned literals, and the audit is now a hard CI gate #5551

The "no purple, ever" law becomes enforced reality. ~45 files, every banned-family literal (hue 225–305, chroma ≥ 0.10) replaced with intensity-matched tokens:

• Pale-lavender text → var(--accent); severity-indigo → var(--blue); all seven CTA gradients → var(--accent-gradient); purple rgba chips → accent color-mix at their original alphas; the admin hairline joins the standard evergreen one; diff-view's #d2a8ff syntax color reads evergreen; standups loses both its purple accent and ~30 dark-hex token fallbacks; the indigo dark slabs in components.tsx (CI failure card) and editor.tsx (AI explain panel) become proper bg-inset/border/text tokens. Zero exemption markers needed.
• Integration honesty: the agent's sweep ran under the pre-Wave-0 hue window (250–300) and reported zero; re-measuring under the corrected instrument found 17 surviving indigo-range literals (#a5b4fc, #1e40af, #5b7bff, #c4cdfa class), finished during integration. The design-audit.mjs conflict resolved in favor of the stricter merged scanner.
• The gate: scripts/ci-tests.sh runs the design audit before the test suite — set -euo pipefail makes any banned literal fail every CI run from now on. This defect class cannot be reintroduced.

Final reading: [design-audit] 0 banned-family literal(s), exit 0. Typecheck clean; 272 tests across 29 touched-file suites green in the agent pass, +63 at integration. The CI run for this very PR is the gate's first live firing.