Nicholai/fix conversations context (#83)

* fix: extract useConversations hook to dedicated context file

Move the conversations context and hook from the layout file to
src/contexts/conversations-context.tsx. Next.js layouts cannot export
hooks or types - only the default component export is allowed.

* fix(build): prevent esbuild from bundling memory-provider

The memory-provider module imports better-sqlite3, a native Node.js
module that cannot run in Cloudflare Workers. This causes OpenNext
build failures when esbuild tries to resolve the module.

Changes:
- Use dynamically constructed import path to prevent static analysis
- Remove memory provider from getServerDb (never used on Cloudflare)
- Add memory-provider to serverExternalPackages in next.config.ts

* fix(lint): rename module variable to loadedModule

The variable name 'module' is reserved in Next.js and causes ESLint
error @next/next/no-assign-module-variable.

* fix(conversations): use drizzle query for organization members

---------

Co-authored-by: Nicholai <nicholaivogelfilms@gmail.com>

src/app/actions/conversations.ts

@@ -11,7 +11,7 @@ import {
   type NewChannelMember,
   type NewChannelReadState,
 } from "@/db/schema-conversations"
-import { users } from "@/db/schema"
+import { users, organizationMembers } from "@/db/schema"
 import { getCurrentUser } from "@/lib/auth"
 import { requirePermission } from "@/lib/permissions"
 import { revalidatePath } from "next/cache"
@@ -170,9 +170,9 @@ export async function createChannel(data: {
 
     // get user's organization
     const orgMember = await db
-      .select({ organizationId: sql<string>`organization_id` })
-      .from(sql`organization_members`)
-      .where(sql`user_id = ${user.id}`)
+      .select({ organizationId: organizationMembers.organizationId })
+      .from(organizationMembers)
+      .where(eq(organizationMembers.userId, user.id))
       .limit(1)
       .then((rows) => rows[0] ?? null)