docs: update AGENTS.md and README.md with accurate project details

- Root AGENTS.md: add build pipeline, Makefile targets, full directory listing
- Backend AGENTS.md: add architecture layout, API routes table, streaming/store
  patterns, missing deps (jsonschema-go, values pkg, types pkg)
- Frontend AGENTS.md: add architecture layout, missing deps (marked, highlight.js),
  Alpine component pattern, build pipeline details
- README.md: add env var config table, Docker/Make workflows, dev setup,
  thinking support, token stats, structured output, llama.cpp timings

AGENTS.md

@@ -5,15 +5,31 @@ This repository is a **monorepo** with two main packages that can be built and r
 ## Directory Structure
 
 ```
-├── frontend/        # Client‑side TypeScript application
-├── backend/         # Server‑side Go micro‑service
-├── .envrc, flake.nix, README.md
+├── frontend/        # TypeScript + Alpine.js + Tailwind CSS client
+├── backend/         # Go HTTP server with embedded frontend assets
+├── Makefile         # Orchestrates frontend → backend build pipeline
+├── Dockerfile       # Multi-stage Docker build
+├── .drone.yml       # CI pipeline (tests + Docker publish)
+├── flake.nix        # Nix dev shell (Go, Bun, LSPs, linters)
 └── …
 ```
 
+## Build Pipeline
+
+The frontend builds to `frontend/public/dist/`, then `make frontend` copies the full `frontend/public/` tree into `backend/web/static/` where it gets embedded into the Go binary via `//go:embed`.
+
+```bash
+make all        # Build frontend + backend
+make frontend   # Build frontend, copy to backend/web/static/
+make backend    # Build Go binary (requires frontend assets)
+make dev        # Run both with hot-reload
+make tests      # Run Go tests
+make docker     # Build Docker image
+```
+
 ## Package Details
 
 See package‑specific instructions:
 
-- **frontend/** - `@frontend/AGENTS.md`
-- **backend/** - `@backend/AGENTS.md`
+- **frontend/** — `@frontend/AGENTS.md`
+- **backend/** — `@backend/AGENTS.md`