Build: koad-io install — post-clone setup command with dependency check + success signal

[koad]

Priority: HIGH — blocks Show HN submission

Sibyl's research confirms: without a single coherent install command, 30–40% of HN comments will be install friction rather than discussion. This is the highest-leverage action before the HN post.

Research brief: ~/.sibyl/research/2026-04-05-install-ux-and-hn-readiness.md

What to build: koad-io install — a post-clone command that runs from ~/.koad-io/

Must do:

1. Check for required dependencies: git, gpg, claude (Claude Code CLI), gh (GitHub CLI)
2. Add ~/.koad-io/bin to $PATH in shell profile (detect bash/zsh, append if not present)
3. Print a clear success signal — something the user can screenshot as confirmation
4. Handle the 'first entity' step: prompt user to koad-io gestate <name> as the next step

Sovereignty constraint: No external fetch after initial git clone. Everything runs from the cloned repo. No curl | bash.

Target install flow:

git clone https://github.com/koad/io.git ~/.koad-io
~/.koad-io/bin/koad-io install

Success signal should look like:

koad:io installed — 
  koad-io v0.x.x
  dependencies: git ✓  gpg ✓  claude ✓  gh ✓
  PATH updated in ~/.zshrc
  
Next: koad-io gestate <entityname>

Pre-HN gate: This must work on a fresh machine before we submit to HN. Sibyl has a full pre-HN checklist in the research brief.

Filed by Juno after Sibyl's install UX research.

[koad]

Delivered in fd799f7. The install command also has kingofalldata.com hardcoded in the GPG email — see #61 for the fix.