docs: create AGENTS.md for AI agents and remove outdated CLAUDE.md

- Remove outdated CLAUDE.md with obsolete architecture references
- Create comprehensive AGENTS.md covering:
  - Backend: Go, gRPC, Connect RPC, store layer, migrations
  - Frontend: React, React Query, Context API, state management
  - Development commands, workflows, and testing patterns
  - Code conventions, configuration, CI/CD, and security notes

CLAUDE.md

-# Memos Codebase Guide
-
-## Project Overview
-
-Memos is a self-hosted knowledge management platform with a Go backend and React frontend. The architecture uses gRPC for internal communication with REST access via gRPC-Gateway.
-
-## Architecture Decision Context
-
-**Why gRPC + gRPC-Gateway?**
-- Native gRPC for performance, REST API for compatibility
-- Both protocols served on same port via `cmux` connection multiplexer
-- Frontend uses gRPC-Web (`nice-grpc-web`) for type-safe API calls
-
-**Why multi-database support?**
-- Store interface (`store/driver.go`) abstracts persistence
-- Three implementations: SQLite (default), MySQL, PostgreSQL
-- Each driver has its own migration files in `store/db/{driver}/migration/`
-- Schema version tracked in `instance_setting` table (key: `bb.general.version`)
-
-**Why React Query + Context for frontend state?**
-- **Server state** (memos, users, attachments) managed by React Query (TanStack Query v5)
-  - Automatic caching, deduplication, and background refetching
-  - Hooks in `web/src/hooks/useMemoQueries.ts`, `useUserQueries.ts`, `useAttachmentQueries.ts`
-- **Client state** (UI preferences, filters) managed by React Context
-  - ViewContext (`web/src/contexts/ViewContext.tsx`) - layout, sort order
-  - MemoFilterContext (`web/src/contexts/MemoFilterContext.tsx`) - filter state
-- **Legacy MobX** still present in some components (gradual migration in progress)
-  - Stores in `web/src/store/` used by unmigrated components
-  - Both systems coexist during transition period
-
-## Critical Development Commands
-
-**Backend:**
-```bash
-go run ./cmd/memos --mode dev --port 8081    # Start dev server
-go test ./...                                 # Run tests
-golangci-lint run                            # Lint
-```
-
-**Frontend:**
-```bash
-cd web && pnpm dev                           # Start dev server (React Query devtools at bottom-left)
-cd web && pnpm lint:fix                      # Lint and fix
-cd web && pnpm release                       # Build and copy to backend
-```
-
-**Protocol Buffers:**
-```bash
-cd proto && buf generate                     # Regenerate Go + TypeScript from .proto
-```
-
-## Frontend State Management
-
-**Using React Query (Server State):**
-```typescript
-// Fetch memos
-import { useMemos, useMemo } from "@/hooks/useMemoQueries";
-const { data: memos, isLoading } = useMemos({ filter });
-const { data: memo } = useMemo(memoName);
-
-// Mutations
-import { useCreateMemo, useUpdateMemo } from "@/hooks/useMemoQueries";
-const { mutate: createMemo } = useCreateMemo();
-const { mutate: updateMemo } = useUpdateMemo();
-```
-
-**Using Context (Client State):**
-```typescript
-// View preferences
-import { useView } from "@/contexts/ViewContext";
-const { layout, setLayout, orderByTimeAsc, toggleSortOrder } = useView();
-
-// Filters
-import { useMemoFilter } from "@/contexts/MemoFilterContext";
-const { filter, updateFilter } = useMemoFilter();
-```
-
-**React Query DevTools:**
-- Available in dev mode at bottom-left corner
-- Inspect query cache, mutations, and refetch behavior
-- Query keys organized by resource: `memoKeys`, `userKeys`, `attachmentKeys`
-
-**Migration Status:**
-- ✅ Migrated: Home, MemoDetail, UserProfile, Inboxes pages
-- 🔄 In Progress: Remaining pages and components (gradual migration)
-- See `web/scripts/migration-guide.md` for migration patterns
-
-## Key Workflows
-
-**Modifying APIs:**
-1. Edit `.proto` files in `proto/api/v1/`
-2. Run `buf generate` to regenerate code
-3. Implement in `server/router/api/v1/`
-4. Frontend types auto-update in `web/src/types/proto/`
-
-**Database Schema Changes:**
-1. Create migration files: `store/migration/{sqlite,mysql,postgres}/{version}/NN__description.sql`
-2. Update `LATEST.sql` in each driver directory
-3. Schema version auto-determined from migration files
-4. If adding new tables/models, also update `store/driver.go` interface and implementations
-
-**Authentication Flow:**
-- Interceptor runs on all gRPC methods (`server/router/api/v1/acl.go`)
-- Public endpoints listed in `acl_config.go`
-- Supports both session cookies and JWT bearer tokens
-
-## Critical Path Components
-
-**Entry point:** `cmd/memos/` starts the server
-**API layer:** `server/router/api/v1/` implements gRPC services
-**Data layer:** `store/` handles all persistence
-**Frontend:** `web/src/` React app with React Query + Context (migrating from MobX)
-
-## Testing Expectations
-
-Go tests are required for store and API changes. Frontend relies on TypeScript checking and manual validation.
-
-Run `go test ./store/...` and `go test ./server/router/api/v1/test/...` before committing backend changes.
-
-## Configuration
-
-Backend accepts flags or `MEMOS_*` environment variables:
-- `--mode` / `MEMOS_MODE`: `dev`, `prod`, `demo`
-- `--port` / `MEMOS_PORT`: HTTP/gRPC port (default: 5230)
-- `--data` / `MEMOS_DATA`: Data directory (default: ~/.memos)
-- `--driver` / `MEMOS_DRIVER`: `sqlite`, `mysql`, `postgres`