Add mDNS Peer Discovery Capability

[lthibault]

This PR adds mDNS (multicast DNS) peer discovery capability to Wetware, allowing nodes to automatically discover and connect to other Wetware instances on the local network without manual configuration.

Features

• --with-mdns capability flag - Enables mDNS peer discovery in both ww shell and ww run commands
• Automatic peer discovery - Discovers other Wetware nodes on the local network using mDNS
• Peer management - Automatically adds discovered peers to the libp2p peerstore
• Conditional initialization - mDNS service only starts when the capability flag is enabled
• Proper lifecycle management - Clean startup and shutdown of mDNS services

Implementation Details

Dependencies

• Updated libp2p to v0.43.0 for mDNS support
• Added libp2p/zeroconf/v2 for mDNS implementation
• Updated related dependencies for compatibility

Core Changes

1. Capability Flag (cmd/internal/flags/flags.go)

&cli.BoolFlag{
    Name:     "with-mdns",
    Category: "CAPABILITIES", 
    Usage:    "grant mDNS peer discovery capability",
    EnvVars:  []string{"WW_WITH_MDNS"},
}

2. mDNS Implementation (cmd/ww/run/env.go)

• Added MDNS field to EnvConfig and Env structs
• Implemented MDNSPeerHandler to manage discovered peers
• Added conditional mDNS service initialization in EnvConfig.New()
• Integrated mDNS service lifecycle with environment cleanup

3. Command Integration

• Run command: Passes --with-mdns flag to EnvConfig
• Shell command: Forwards --with-mdns flag to run subprocess

Usage

Enable mDNS in Shell Mode

ww shell --with-mdns

Enable mDNS in Run Mode

ww run --with-mdns /path/to/binary

Enable All Capabilities (including mDNS)

ww shell --with-all

Testing

The implementation has been tested to ensure:

• ✅ mDNS service only starts when --with-mdns flag is used
• ✅ No mDNS service created when flag is not provided
• ✅ Proper logging when mDNS service starts
• ✅ Clean integration with existing capability system
• ✅ Both shell and run commands work correctly

Architecture

The mDNS discovery is implemented in the run process environment, following the existing pattern where:

1. The shell command spawns a run subprocess
2. The run process manages the libp2p host and mDNS service
3. Capability flags are passed from shell to run process
4. mDNS service automatically discovers peers and adds them to the peerstore

Backward Compatibility

• No breaking changes to existing functionality
• mDNS is opt-in via capability flag
• Existing commands work unchanged without the flag

[mikelsr]

In merging #21 and #22 I seem to have caused merge conflicts

[mikelsr]

Solved!