feat: make extension system packageable via enriched ExtensionContext

Enrich ExtensionContext with supabase, emit(), settings, storage, log,
and services so extensions can receive everything through dependency
injection instead of importing core modules directly.

- Add context factory and inject context into event handlers via registry
- Move supplier invoice journal entry creation to core event handler
- Add services.ingestTransactions to ExtensionContext for enable-banking
- Create catch-all API route for extension-declared apiRoutes
- Migrate 5 extensions to accept context with dynamic import fallbacks

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/extensions/types.ts

@@ -1,5 +1,6 @@
-import type { CoreEventType } from '@/lib/events/types'
-import type { EntityType } from '@/types'
+import type { SupabaseClient } from '@supabase/supabase-js'
+import type { CoreEvent, CoreEventType } from '@/lib/events/types'
+import type { EntityType, RawTransaction, IngestResult } from '@/types'
 
 // ============================================================
 // Extension Marketplace Types
@@ -63,7 +64,7 @@ export interface RouteDefinition {
 export interface ApiRouteDefinition {
   method: 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH'
   path: string
-  handler: (request: Request) => Promise<Response>
+  handler: (request: Request, ctx?: ExtensionContext) => Promise<Response>
 }
 
 /** Sidebar navigation item added by an extension */
@@ -112,13 +113,44 @@ export interface MappingRuleTypeDefinition {
 export interface ExtensionEventHandler {
   eventType: CoreEventType
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  handler: (payload: any) => Promise<void> | void
+  handler: (payload: any, ctx?: ExtensionContext) => Promise<void> | void
 }
 
-/** Context passed to extension lifecycle hooks */
+/** Logger interface for extensions */
+export interface ExtensionLogger {
+  info(message: string, ...args: unknown[]): void
+  warn(message: string, ...args: unknown[]): void
+  error(message: string, ...args: unknown[]): void
+}
+
+/** Settings accessor for extension-scoped key-value data */
+export interface ExtensionSettings {
+  get<T>(key?: string): Promise<T | null>
+  set<T>(key: string, value: T): Promise<void>
+}
+
+/** Storage accessor wrapping Supabase storage */
+export interface ExtensionStorage {
+  download(bucket: string, path: string): Promise<{ data: Blob | null; error?: string }>
+  upload(bucket: string, path: string, data: ArrayBuffer, options?: { contentType?: string }): Promise<{ path: string; error?: string }>
+  getPublicUrl(bucket: string, path: string): string
+}
+
+/** Core services exposed to extensions */
+export interface ExtensionServices {
+  ingestTransactions(supabase: SupabaseClient, userId: string, raw: RawTransaction[]): Promise<IngestResult>
+}
+
+/** Context passed to extension lifecycle hooks and event handlers */
 export interface ExtensionContext {
   userId: string
   extensionId: string
+  supabase: SupabaseClient
+  emit(event: CoreEvent): Promise<void>
+  settings: ExtensionSettings
+  storage: ExtensionStorage
+  log: ExtensionLogger
+  services: ExtensionServices
 }
 
 /**