docs(project): add README, CI workflow, migration guide, and fix asset docs

- README.md: player-facing install, controls, features, and test instructions
- .github/workflows/ci.yml: clippy + headless tests + release build on push/PR
- solitaire_server/migrations/README.md: naming convention and workflow for
  adding future schema migrations
- ARCHITECTURE.md §14: rewrite Asset Pipeline to reflect procedural rendering
  (no image files used; audio only, embedded via include_bytes!)
- ARCHITECTURE.md §2 / §13: fix workspace structure and audio file listing
- CLAUDE.md: clarify asset embedding rule (audio only; visuals are procedural)
- server_tests.rs: add auth_rate_limit_returns_429_on_11th_request test using
  build_router() (rate limiting ON) to verify the GovernorLayer is wired correctly

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

README.md

@@ -0,0 +1,73 @@
+# Solitaire Quest
+
+A cross-platform Klondike Solitaire game written in Rust, featuring a full progression system with XP, levels, achievements, daily challenges, and optional self-hosted sync so your stats follow you across machines.
+
+## Features
+
+- **Klondike Solitaire** — Draw One and Draw Three modes
+- **Progression** — XP, levels, unlockable card backs and backgrounds
+- **18 Achievements** — including secret ones
+- **Daily Challenge** — server-seeded so every player worldwide gets the same deal
+- **Leaderboard** — opt-in, powered by your own self-hosted server
+- **Special Modes** (unlocked at level 5): Zen, Time Attack, Challenge
+- **Sync** — pull/push stats across devices via a self-hosted server
+- **Color-blind mode** — blue tint on red-suit cards
+
+## Building
+
+**Prerequisites**
+
+- Rust stable toolchain (`rustup install stable`)
+- Linux: `libasound2-dev libudev-dev libxkbcommon-dev`
+- macOS: Xcode Command Line Tools
+
+```bash
+# Fast development build
+cargo run -p solitaire_app --features bevy/dynamic_linking
+
+# Release build
+cargo build -p solitaire_app --release
+./target/release/solitaire_app
+```
+
+## Controls
+
+| Key | Action |
+|---|---|
+| Left click / drag | Move cards |
+| Right click | Highlight legal moves for a card |
+| Space / D | Draw from stock |
+| Z / Ctrl+Z | Undo |
+| N | New game |
+| S | Stats overlay |
+| A | Achievements overlay |
+| P | Profile overlay |
+| O | Settings |
+| L | Leaderboard |
+| H | Help / controls |
+| Enter | Auto-complete (when badge is lit) |
+| Escape | Pause / clear selection |
+| Arrow keys | Navigate card selection |
+
+## Sync Server (optional)
+
+To sync stats across machines, run the self-hosted server. See [README_SERVER.md](README_SERVER.md) for setup instructions.
+
+Once the server is running, open **Settings → Sync Backend**, enter the server URL and your username, and register an account from within the game.
+
+## Running Tests
+
+```bash
+# All tests
+cargo test --workspace
+
+# Just game logic (no display required)
+cargo test -p solitaire_core -p solitaire_sync -p solitaire_data -p solitaire_server
+
+# Lint
+cargo clippy --workspace -- -D warnings
+```
+
+## License
+
+MIT — see [LICENSE](LICENSE).