Add plain-English Windows install/join guide for end users

A non-technical walkthrough to send alongside the installer: covers the
SmartScreen "unknown publisher" warning, the firewall/desktop-shortcut
checkboxes, and joining/creating a call via room tickets. Uses the actual UI
labels (Join Room / Create New Room / Copy Ticket / Leave Room).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packaging/windows/INSTALL.md

@@ -0,0 +1,82 @@
+# PeerSpeak — how to install and join a call (Windows)
+
+PeerSpeak is a little voice-chat app — like a private phone call over the
+internet, with no account, no signup, and no company in the middle. You install
+it once, then you and I connect directly to each other.
+
+---
+
+## 1. Install it
+
+1. Double-click **`peerspeak-0.2.0-setup.exe`** (the file I sent you).
+
+2. **Windows will probably show a blue "Windows protected your PC" warning.**
+   This is normal — it shows up for any app that isn't from a big company with a
+   paid certificate. It is **not** a virus warning.
+   - Click **More info**
+   - Then click **Run anyway**
+
+3. Windows will ask *"Do you want to allow this app to make changes?"* — click
+   **Yes**.
+
+4. The setup window opens. Just keep clicking **Next**. Two checkboxes you'll
+   see along the way:
+   - **"Allow PeerSpeak through Windows Firewall"** — leave this **checked**
+     (it lets the call connect without interruptions).
+   - **"Create a desktop shortcut"** — check it if you'd like an icon on your
+     desktop.
+
+5. Click **Install**, then **Finish**. PeerSpeak opens.
+
+That's it — it's installed. You can find it again any time from the **Start
+menu** (search "PeerSpeak").
+
+---
+
+## 2. Get on a call with me
+
+PeerSpeak connects two people using a **room ticket** — a long code that acts
+like a one-time phone number for a specific call.
+
+**The simple way (I host):**
+
+1. I'll create a room and send you a **ticket** (a long jumble of letters and
+   numbers).
+2. Copy the whole ticket I sent you.
+3. In PeerSpeak, paste it into the **"Join Room"** box near the bottom and press
+   **Join**.
+4. You're in — you should see both our names listed, and we can talk.
+
+**If you want to host instead:**
+
+1. Type a room name and click **Create New Room**.
+2. PeerSpeak gives you a **ticket** — click **Copy Ticket** and send it to me.
+3. I paste it on my end and join you.
+
+Either way works the same; it just depends on who makes the room.
+
+---
+
+## 3. While you're on a call
+
+- **Your microphone** is on by default. There's a **mute** button if you need
+  it.
+- The first time, Windows might ask for permission to use your **microphone** —
+  click **Yes / Allow**.
+- If you can't hear me or I can't hear you, open **Settings** (top right) and
+  check that the right **microphone** and **speakers/headphones** are selected.
+- To hang up, click **Leave Room**.
+
+---
+
+## Troubleshooting
+
+- **"I don't hear anything."** Open Settings and pick the correct microphone and
+  output device. Headphones are best — they prevent echo.
+- **"It won't connect."** Make sure you pasted the *entire* ticket (they're
+  long and easy to cut off). If it still won't connect, we may just need a fresh
+  ticket — they're meant to be used right away.
+- **The blue warning again.** Same as install: **More info → Run anyway**. It's
+  the unsigned-app warning, not malware.
+
+Any trouble, just message me and we'll sort it out.