Add Agent Mail documentation and bash-agent integration

- Added Agent Mail section to QUICKSTART.md with benefits and setup
- Integrated Agent Mail into bash-agent example with reservation/notification
- Added multi-agent usage instructions to bash-agent README
- Closed bd-eimz (QUICKSTART), bd-fkdw (bash-agent), bd-sc57 (production)
- Completed bd-nl8z documentation epic

Amp-Thread-ID: https://ampcode.com/threads/T-5b0d67ff-5eb2-41b3-bc9b-7f33719e0c85
Co-authored-by: Amp <amp@ampcode.com>

examples/bash-agent/README.md

@@ -10,6 +10,7 @@ A bash script demonstrating how an AI agent can use bd to manage tasks autonomou
 - Random issue creation to simulate real agent behavior
 - Dependency linking with `discovered-from`
 - Statistics display
+- **Optional Agent Mail integration** for multi-agent coordination
 
 ## Prerequisites
 
@@ -20,6 +21,8 @@ A bash script demonstrating how an AI agent can use bd to manage tasks autonomou
 
 ## Usage
 
+### Basic (Single Agent)
+
 ```bash
 # Make executable
 chmod +x agent.sh
@@ -31,6 +34,29 @@ chmod +x agent.sh
 ./agent.sh 20
 ```
 
+### Multi-Agent Mode (with Agent Mail)
+
+```bash
+# Terminal 1: Start Agent Mail server
+cd ~/src/mcp_agent_mail
+source .venv/bin/activate
+python -m mcp_agent_mail.cli serve-http
+
+# Terminal 2: Run first agent
+export BEADS_AGENT_MAIL_URL=http://127.0.0.1:8765
+export BEADS_AGENT_NAME=bash-agent-1
+export BEADS_PROJECT_ID=my-project
+./agent.sh 10
+
+# Terminal 3: Run second agent (simultaneously)
+export BEADS_AGENT_MAIL_URL=http://127.0.0.1:8765
+export BEADS_AGENT_NAME=bash-agent-2
+export BEADS_PROJECT_ID=my-project
+./agent.sh 10
+```
+
+Agents will coordinate via Agent Mail to prevent claiming the same issues.
+
 ## What It Does
 
 The agent runs in a loop: