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

memento-note/lib/ai/router.ts

@@ -0,0 +1,172 @@
+/**
+ * Central synchronous AI gateway routing (Story 3.2 — FR17 / NFR-P3).
+ *
+ * Future (Story 3.5 BYOK): plug user-scoped API keys into resolveAiRoute output / factory instantiation.
+ *
+ * Non-goals here (by design):
+ * - Multi-provider HTTP fallback on 429/500 → Story 3.3
+ * - BYOK / UserAPIKey decryption → Story 3.5 (extension seam: same resolve output + key source later)
+ */
+
+export type AiFeatureLane = 'chat' | 'tags' | 'embedding'
+
+export type AiGatewayProvider =
+  | 'ollama'
+  | 'openai'
+  | 'google'
+  | 'minimax'
+  | 'glm'
+  | 'custom'
+  | 'deepseek'
+  | 'openrouter'
+  | 'mistral'
+  | 'zai'
+  | 'lmstudio'
+  | 'anthropic'
+  | 'anthropic_custom'
+
+export interface ResolvedAiRoute {
+  lane: AiFeatureLane
+  providerType: AiGatewayProvider
+  modelName: string
+  embeddingModelName: string
+  ollamaBaseUrl?: string
+  meta: {
+    resolveMs?: number
+  }
+}
+
+export const VALID_PROVIDERS = new Set<string>([
+  'ollama', 'openai', 'google', 'minimax', 'glm', 'custom',
+  'deepseek', 'openrouter', 'mistral', 'zai', 'lmstudio',
+  'anthropic', 'anthropic_custom',
+])
+
+const PROVIDER_MODEL_DEFAULTS: Record<string, { model: string; embeddingModel: string }> = {
+  ollama:            { model: 'granite4:latest',              embeddingModel: 'embeddinggemma:latest' },
+  openai:            { model: 'gpt-4o-mini',                  embeddingModel: 'text-embedding-3-small' },
+  anthropic:         { model: 'claude-sonnet-4-6-20250514',   embeddingModel: '' },
+  anthropic_custom:  { model: 'claude-sonnet-4-6-20250514',   embeddingModel: '' },
+  deepseek:          { model: 'deepseek-chat',                embeddingModel: '' },
+  openrouter:        { model: 'openai/gpt-4o-mini',          embeddingModel: 'openai/text-embedding-3-small' },
+  google:            { model: 'gemini-1.5-flash',             embeddingModel: 'text-embedding-004' },
+  mistral:           { model: 'mistral-small-latest',         embeddingModel: 'mistral-embed' },
+  zai:               { model: 'gpt-4o-mini',                  embeddingModel: 'text-embedding-3-small' },
+  minimax:           { model: 'abab6.5-chat',                 embeddingModel: '' },
+  glm:               { model: 'glm-4',                        embeddingModel: 'embedding-2' },
+  lmstudio:          { model: '',                              embeddingModel: '' },
+  custom:            { model: '',                              embeddingModel: '' },
+}
+
+function pick(config: Record<string, string>, key: string): string | undefined {
+  const v = config[key]
+  if (v != null && v !== '') return v
+  const e = process.env[key]
+  return e != null && e !== '' ? e : undefined
+}
+
+function cfgOnly(config: Record<string, string>, key: string): string | undefined {
+  const v = config[key]
+  return v != null && v !== '' ? v : undefined
+}
+
+const VALID_PROVIDER_LIST = [...VALID_PROVIDERS].join(', ')
+
+export function resolveAiRoute(lane: AiFeatureLane, config: Record<string, string>): ResolvedAiRoute {
+  let providerRaw: string | undefined
+  let modelKey: string
+  let ollamaBaseUrl: string | undefined
+
+  if (lane === 'tags') {
+    providerRaw =
+      pick(config, 'AI_PROVIDER_TAGS') ||
+      pick(config, 'AI_PROVIDER_EMBEDDING') ||
+      pick(config, 'AI_PROVIDER')
+    modelKey = 'AI_MODEL_TAGS'
+    ollamaBaseUrl = cfgOnly(config, 'OLLAMA_BASE_URL_TAGS') || cfgOnly(config, 'OLLAMA_BASE_URL')
+    if (!providerRaw) {
+      throw new Error(
+        'AI_PROVIDER_TAGS is not configured. Please set it in the admin settings or environment variables. ' +
+          'Options: ' + VALID_PROVIDER_LIST
+      )
+    }
+  } else if (lane === 'embedding') {
+    providerRaw =
+      pick(config, 'AI_PROVIDER_EMBEDDING') ||
+      pick(config, 'AI_PROVIDER_TAGS') ||
+      pick(config, 'AI_PROVIDER')
+    modelKey = 'AI_MODEL_EMBEDDING'
+    ollamaBaseUrl = cfgOnly(config, 'OLLAMA_BASE_URL_EMBEDDING') || cfgOnly(config, 'OLLAMA_BASE_URL')
+    if (!providerRaw) {
+      throw new Error(
+        'AI_PROVIDER_EMBEDDING is not configured. Please set it in the admin settings or environment variables. ' +
+          'Options: ' + VALID_PROVIDER_LIST
+      )
+    }
+  } else {
+    providerRaw =
+      pick(config, 'AI_PROVIDER_CHAT') ||
+      pick(config, 'AI_PROVIDER_TAGS') ||
+      pick(config, 'AI_PROVIDER_EMBEDDING') ||
+      pick(config, 'AI_PROVIDER')
+    modelKey = 'AI_MODEL_CHAT'
+    ollamaBaseUrl =
+      cfgOnly(config, 'OLLAMA_BASE_URL_CHAT') ||
+      cfgOnly(config, 'OLLAMA_BASE_URL_TAGS') ||
+      cfgOnly(config, 'OLLAMA_BASE_URL_EMBEDDING') ||
+      cfgOnly(config, 'OLLAMA_BASE_URL')
+    if (!providerRaw) {
+      throw new Error(
+        'AI_PROVIDER_CHAT is not configured. Please set it in the admin settings or environment variables. ' +
+          'Options: ' + VALID_PROVIDER_LIST
+      )
+    }
+  }
+
+  const providerType = providerRaw.toLowerCase()
+
+  if (!VALID_PROVIDERS.has(providerType)) {
+    throw new Error(
+      `Unknown AI provider '${providerRaw}'. Valid options: ${VALID_PROVIDER_LIST}`
+    )
+  }
+
+  if (lane === 'embedding' && (providerType === 'anthropic' || providerType === 'anthropic_custom')) {
+    throw new Error(
+      'AI_PROVIDER_EMBEDDING cannot use "anthropic" or "anthropic_custom": these gateways use the Anthropic Messages API only (no embeddings in Memento). Use ollama, openai, or "custom" with MiniMax OpenAI URL https://api.minimax.io/v1 for embeddings.'
+    )
+  }
+
+  const defaults = PROVIDER_MODEL_DEFAULTS[providerType] || { model: '', embeddingModel: '' }
+  const modelName = pick(config, modelKey) || defaults.model
+  const embeddingModelName = pick(config, 'AI_MODEL_EMBEDDING') || defaults.embeddingModel
+
+  return {
+    lane,
+    providerType: providerType as AiGatewayProvider,
+    modelName,
+    embeddingModelName,
+    ollamaBaseUrl,
+    meta: {},
+  }
+}
+
+export function resolveAiRouteWithTiming(lane: AiFeatureLane, config: Record<string, string>): ResolvedAiRoute {
+  const t0 = performance.now()
+  const route = resolveAiRoute(lane, config)
+  const resolveMs = performance.now() - t0
+  return {
+    ...route,
+    meta: { ...route.meta, resolveMs },
+  }
+}
+
+export function formatAiRouteDebug(route: ResolvedAiRoute): string {
+  return JSON.stringify({
+    lane: route.lane,
+    providerType: route.providerType,
+    modelId: route.modelName,
+    embeddingModelId: route.embeddingModelName,
+    resolveMs: route.meta.resolveMs,
+  })
+}