Installation friction: PATH, zshrc, progress, toolchain warning

[Keinberger]

Context

Multiple issues reported during Miden Day related to midenup installation experience.

Items

• PATH directives in docs are wrong. Should point to toolchains/stable/bin, not midenup/bin.
• ~/.zshrc doesn't exist on fresh macOS, midenup setup fails silently.
• midenup install stable takes 20-30 minutes with no progress indicator. Users ctrl-C thinking it's stuck.
• "WARNING: new is an alias from component cargo-miden, which is installed but is not part of the current active toolchain" is confusing for both humans and AI agents.

[lima-limon-inc]

"WARNING: new is an alias from component cargo-miden, which is installed but is not part of the current active toolchain" is confusing for both humans and AI agents.

This issue is being addressed in this PR: #173

[lima-limon-inc]

Update on this issue:

• PATH directives in docs are wrong. Should point to toolchains/stable/bin, not midenup/bin: This has been addressed in PATH not configured after midenup install stable on Ubuntu docs#181
• ~/.zshrc doesn't exist on fresh macOS, midenup setup fails silently.
• midenup install stable takes 20-30 minutes with no progress indicator. Users ctrl-C thinking it's stuck. This is being tracked here: feat: add artifacts in all the repositories #177
• "WARNING: new is an alias from component cargo-miden, which is installed but is not part of the current active toolchain" is confusing for both humans and AI agents. This bug was addressed here: fix: warning regarding current toolchain #173.

For the addressed items, I'm marking them as done.

[bitwalker]

I think we should show the output from cargo when installing components via cargo install - it will always be an option to install components that way, and we need useful output. There's not really a useful way to measure progress though, so it's best to simply show what Cargo is doing IMO.