docs: add public documentation for contributors and users

Created 12 public docs derived from internal vault:
- Setup guides: quick-start, server-configuration, livekit-setup, deployment
- Networking: port-forwarding, tailscale
- References: api, protocol, schema, client-architecture
- Community: contributing, security

Updated .gitignore to only exclude docs/brain/ (internal vault),
allowing docs/ to be tracked. Updated README with expanded quick
start, voice/video setup, networking ports, and doc links.

docs/quick-start.md

@@ -0,0 +1,66 @@
+# Quick Start Guide
+
+Get OwnCord up and running in minutes.
+
+## Prerequisites
+
+- **Windows 10+** (x64)
+- **Go 1.25+** (only if building the server from source)
+- **Node.js 20+** (only if building the client from source)
+- **Rust / Cargo** (only if building the Tauri client from source)
+- **LiveKit Server** binary (optional, for voice/video) -- see [LiveKit Setup](livekit-setup.md)
+
+## Step 1: Download
+
+Get the latest release from GitHub Releases. Download `chatserver.exe` and the `OwnCord` installer.
+
+Or build from source:
+
+```bash
+# Server
+cd Server
+go build -o chatserver.exe -ldflags "-s -w -X main.version=1.0.0" .
+
+# Client
+cd Client/tauri-client
+npm install
+npm run tauri build
+```
+
+## Step 2: Run the Server
+
+Run `chatserver.exe`. On first run:
+
+1. `config.yaml` is created in the working directory with default settings
+2. `data/` directory is created for the database, TLS certs, uploads, and backups
+3. A self-signed TLS certificate is generated automatically
+4. SQLite database is created and all migrations are applied
+5. All user statuses are reset to offline (clean slate)
+
+The server starts on `https://0.0.0.0:8443`.
+
+See [Server Configuration](server-configuration.md) for the full config key reference and environment variable overrides.
+
+## Step 3: Admin Setup
+
+Open `https://localhost:8443/admin` in a browser. The first-run setup page will prompt you to create the Owner account (username + password). This user gets the Owner role with full server control.
+
+## Step 4: Create Invites
+
+In the admin panel, go to invite management and generate invite codes for your friends.
+
+## Step 5: Connect Clients
+
+Friends install OwnCord, enter your server address (IP or domain + port 8443), and redeem their invite code to register.
+
+The client uses TOFU (Trust On First Use) for self-signed certificates -- it will prompt to trust the server's certificate on first connection, then pin it for future sessions.
+
+## Networking
+
+If friends are outside your local network, see the [Port Forwarding Guide](port-forwarding.md) or use [Tailscale](tailscale.md) for zero-config networking.
+
+## Next Steps
+
+- [Server Configuration](server-configuration.md) -- customize ports, TLS, uploads, voice
+- [Deployment Guide](deployment.md) -- production hardening, backups, monitoring, Windows service setup
+- [LiveKit Setup](livekit-setup.md) -- enable voice and video chat