Rename forge-cli binary to forge

[titouanmathis]

Summary

Renames the CLI binary from forge-cli to forge for a shorter, more natural command name.

# Before
forge-cli servers list
forge-cli deployments deploy --server 123 --site 456

# After
forge servers list
forge deployments deploy --server 123 --site 456

Changes

• Binary name: forge-cli → forge (in packages/cli/package.json bin field)
• Help text & usage strings: all 20+ command handlers and help files updated
• Shell completion: function names (_forge_completions, _forge), file paths (completions/forge, _forge, forge.fish), and all complete -c directives updated
• Error messages: all validation/config error hints updated
• Tests: all test expectations updated (completion, config, errors, help)
• Docs: README (root + cli), CONTRIBUTING, CLAUDE.md, CHANGELOG

What stays the same

• Package name: still @studiometa/forge-cli on npm
• Directory: still packages/cli/
• All other packages: untouched

Breaking Change

Users who have forge-cli in scripts or shell aliases must update to forge. Shell completions need to be reinstalled via forge completion bash/zsh/fish.

Closes #82

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.80%. Comparing base (266782f) to head (a9e5988).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #83   +/-   ##
=======================================
  Coverage   99.80%   99.80%           
=======================================
  Files         225      225           
  Lines        3624     3624           
  Branches      847      816   -31     
=======================================
  Hits         3617     3617           
  Misses          7        7           

Flag	Coverage Δ
unittests	99.80% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.