feat: design system overhaul — sidebar, AI chats, settings, brainstorm, color cleanup

- Sidebar: dynamic brand-accent colors, brainstorm section restyled
- AI chat general: popup panel with expand/collapse, hides when contextual AI open
- AI chat contextual: tabs reordered (Actions first), X close button, height fix
- Settings: all tabs restyled, 6 new color presets (sage, terracotta, iron, etc.)
- Global color cleanup: emerald/orange hardcoded → brand-accent dynamic
- Brainstorm page: orange → brand-accent throughout
- PageEntry animation component added to key pages
- Floating AI button: bg-brand-accent instead of hardcoded black
- i18n: all 15 locales updated with new AI/billing keys
- Billing: freemium quota tracking, BYOK, stripe subscription scaffolding
- Admin: integrated into new design
- AGENTS.md + CLAUDE.md project rules added

.agent/skills/wds-8-product-evolution/workflow-implement.md

@@ -0,0 +1,80 @@
+---
+name: implement
+description: Code the designed improvement in a new branch
+borrows_from: Phase 5 (development)
+---
+
+# Implement
+
+**Goal:** Implement the approved design in code, working in a dedicated branch like a developer on the team.
+
+---
+
+## INITIALIZATION
+
+### Design Log
+Read `{output_folder}/_progress/00-design-log.md`. Check Current and Backlog for context.
+
+
+## Steps
+
+### Step 1: Load Specification
+
+Read the specification from [D] Design Solution:
+
+- Change summary
+- Component specifications
+- Acceptance criteria
+- Pages affected
+
+### Step 2: Create Branch
+
+Create a feature branch for this improvement:
+
+```
+git checkout -b evolution/[scenario-name]
+```
+
+Naming convention: `evolution/` prefix + kebab-case scenario name.
+
+### Step 3: Understand Current Code
+
+Before writing code, understand what exists:
+
+1. Locate the files for affected pages/views
+2. Read current component implementations
+3. Identify the tech stack patterns (framework, styling approach, state management)
+4. Note any existing design tokens or theme configuration
+
+Present a brief implementation plan:
+- Which files will change
+- What new files are needed (if any)
+- Estimated complexity
+
+### Step 4: Implement Changes
+
+Write the code changes following the specification:
+
+1. **Follow existing patterns** — Match the codebase's conventions, don't introduce new ones
+2. **Minimal changes** — Only change what the specification calls for
+3. **Commit incrementally** — One logical commit per change unit
+4. **Test as you go** — Verify each change works before moving on
+
+For each file changed, explain what was modified and why.
+
+### Step 5: Self-Review
+
+Before handing off:
+
+1. Diff all changes: `git diff evolution/[scenario-name]..main`
+2. Check against specification: every acceptance criterion addressed?
+3. Check for unintended side effects: other pages/components still work?
+4. Clean up: no debug code, no commented-out blocks, no unrelated changes
+
+---
+
+## AFTER COMPLETION
+
+1. Update design log
+2. Suggest next action
+3. Return to activity menu