docs: add Cursor Cloud dev environment instructions (AGENTS.md)

[lyingbug]

Description

Sets up a full local development environment for WeKnora in the Cursor Cloud VM and captures the durable, non-obvious startup/run caveats discovered during setup in a new root AGENTS.md (## Cursor Cloud specific instructions). No application code is changed.

The running dev stack is: Postgres (paradedb) + Redis via docker-compose.dev.yml, the Go backend on the host (make dev-app, :8080), the Vite web UI (make dev-frontend, :5173), and Ollama (:11434) as the local LLM provider for embeddings/chat.

Type of Change

• 📚 Documentation update
• 🔧 Configuration / Build / CI

Related Issue

N/A

Testing

Verified the environment end-to-end:

• Build: make build (standard server) and make build-lite both compile (CGO needs libsqlite3-dev).
• Lint: golangci-lint run works once built with the repo's Go 1.26 toolchain (runs against internal/database/..., surfacing only pre-existing findings).
• Go tests: go test ./internal/handler/... ./internal/types/... -count=1 pass.
• Frontend: npm run test (292 pass) and npm run type-check pass.
• Hello-world (core RAG flow) through the web UI: registered an account + workspace, logged in, created a knowledge base (embedding nomic-embed-text + LLM qwen2.5:0.5b via Ollama), and added a text knowledge entry that was parsed, embedded, and LLM-summarized.

Key findings captured in AGENTS.md: Lite/SQLite mode is broken (stale migrations/sqlite snapshot) so the Postgres stack must be used; Docker 29 on this VM needs fuse-overlayfs + containerd-snapshotter: false; OLLAMA_BASE_URL must point at localhost and SSRF_WHITELIST must include loopback for host-run model config.

Checklist

• Changed source files are formatted
• Targeted tests for the changed packages/components pass
• Self-reviewed the code
• Updated related documentation (README, docs/, Swagger annotations, etc.)

Screenshots / Recordings

Knowledge base list (logged in as weknora_admin):

WeKnora knowledge base list

Demo KB detail with the ingested, embedded and LLM-summarized "Hello WeKnora" entry:

Demo KB with Hello WeKnora entry

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