feat(shell): cut over to libp2p mDNS transport and terminal auth

[lthibault]

Summary

• wire mDNS into host/client libp2p behaviours for local discovery
• replace ww shell stub with live libp2p transport + Terminal(Membrane) auth path
• keep no-arg ww shell as mDNS discovery with deterministic ambiguity handling
• remove --discover from CLI surface (redundant with no-arg discovery)
• update shell/CLI/README/changelog docs and add focused unit tests for selection + peer-id parsing

Notes

• This PR is stacked on refactor(daemon): remove config.glia control plane #480.
• Interactive multi-select UX for multi-candidate discovery remains tracked in ww shell: handle multiple mDNS discovery results with interactive target selection #479.

Validation

• cargo check -p ww --bin ww
• cargo test -p ww --bin ww
• cargo test -p ww --lib

Part of #470 and #468.