Initial commit: pi harness bring-up split out of mempalace-toolkit

Pi-generic config artifacts (no mempalace dependency):
- pi-env.zsh: shell loader sourcing ~/.config/pi/.env for AWS_PROFILE /
  AWS_REGION. POSIX-compatible (works in bash and zsh).
- keybindings.json: mosh/tmux newline bindings (shift+enter, ctrl+j, alt+j).
- settings.example.json: ~/.pi/agent/settings.json template so pi starts
  without --provider/--model. Region-specific (Bedrock inference-profile
  prefix).

install.sh mirrors mempalace-toolkit + opencode-toolkit patterns:
- require_pi_installed: hard exit 4 if ~/.pi/agent/ missing (cannot do
  anything useful; user must install pi first).
- symlink keybindings.json (safe: pi doesn't rewrite it).
- cp pi-env.zsh into ~/.oh-my-zsh/custom/ (portability over symlink,
  that dir is part of dotfiles backups). Print source snippet for bash
  / plain-zsh users.
- settings.example.json NOT installed \u2014 pi rewrites settings.json at
  runtime. check_pi_settings probe prints the cp command instead.
- check_aws_env: gated on settings.json selecting amazon-bedrock; silent
  for non-Bedrock providers or missing settings.
- All probes warn + return 0, never halt.
- Non-destructive: backup on symlink collision, cmp-based drift detection
  on the cp path, uninstall only removes copies whose content still
  matches repo.

Split rationale: opencode-devbox's mempalace opt-out (~300 MB saved)
wants pi available without mempalace. That dependency asymmetry is
cleanest when pi's own config lives in its own repo, same shape as
opencode-toolkit split out earlier today.

The pi\u2194mempalace MCP bridge (mempalace.ts) stays in mempalace-toolkit
where it belongs \u2014 it imports pi's ExtensionAPI but only exists to
bridge to the palace.

Verified on tor-ms22: fresh install \u2192 drift detect \u2192 adopt canonical \u2192
uninstall \u2192 reinstall \u2192 zsh -ic loads AWS vars. Bash fallback path also
tested via HOME=/tmp/fake SHELL=/bin/bash.

LICENSE

@@ -0,0 +1,18 @@
+MIT License
+
+Copyright (c) 2026 joakimp
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and 
+associated documentation files (the "Software"), to deal in the Software without restriction, including 
+without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
+copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the 
+following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial 
+portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT 
+LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO 
+EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER 
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 
+USE OR OTHER DEALINGS IN THE SOFTWARE.