Docs/UX: localhost:7777 not reachable after localnet up — Web UI requires separate ui command

[zheli]

Summary

External tester followed the LocalNet lifecycle guide (zero-to-running), got a healthy demo instance and working Wallet UIs, but http://localhost:7777 returned connection refused.

Expected

Operators who see references to port 7777 (or expect a dashboard after up) know they must run canton-devkit localnet ui (or dpm localnet ui) in a separate process. The lifecycle zero-to-running path should include that step when the Web UI is part of the intended workflow.

Actual

localnet up brings up the Splice stack only. The embedded Web UI is a separate long-running command (localnet ui, default port 7777). The published lifecycle guide does not mention starting the UI, so :7777 looks broken.

Proposed fix

• Add an explicit step to LocalNet lifecycle / zero-to-running (docs/localnet-lifecycle.md and website mirror): start the Web UI with canton-devkit localnet ui, open the printed URL.
• Optionally harden the post-up success hint so localnet ui / the URL read clearly as commands (and use canton-devkit when not under DPM).
• Consider a short FAQ: Why does localhost:7777 refuse to connect?

Out of scope (same feedback thread)

• Amulet Wallet UI button SELF-GRANT FEATURED APP RIGHTS — upstream Splice wallet behavior; reporter notes the same on Canton DevNet.
• Docker Desktop memory reset — host/Docker config, not DevKit.

Context

• Platform: macOS ARM, install via .sh installer
• LocalNet demo otherwise healthy; Wallet UIs reachable