fix: add ~/.npm-global/bin to OpenClaw PATH for gateway, launch, and reconnect (#1972)

* fix: add ~/.npm-global/bin to OpenClaw PATH for gateway, launch, and reconnect

OpenClaw installs to ~/.npm-global/bin/ via npm, but startGateway() and
launchCmd() only included ~/.bun/bin and ~/.local/bin in PATH — so the
`openclaw` binary was never found on non-Fly clouds (DigitalOcean, Hetzner,
AWS, GCP). Fly was unaffected because it uses setupOpenclawBatched() which
correctly includes the npm-global path.

Three fixes:
1. startGateway(): add $HOME/.npm-global/bin to PATH
2. launchCmd(): add $HOME/.npm-global/bin to PATH
3. install(): persist PATH to ~/.bashrc and ~/.zshrc (matching codex/kilocode
   pattern) so reconnects via `spawn openclaw <cloud> --name ...` also work

Closes #1965

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: correct command chaining and idempotency in npm-global PATH setup

- Use curly braces to group grep||echo so PATH append only runs after
  successful npm install (fixes operator precedence bug)
- Skip ~/.zshrc modification when file doesn't exist (avoids creating
  it on non-zsh systems)
- Use grep -qF for literal string matching (no regex interpretation)
- Apply fix to all three affected agents: openclaw, codex, kilocode

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude <claude@anthropic.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: B <6723574+louisgv@users.noreply.github.com>

packages/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@openrouter/spawn",
-  "version": "0.10.25",
+  "version": "0.10.26",
   "type": "module",
   "bin": {
     "spawn": "cli.js"