feat: Experimental Sandbox Support (#101)

* feat: Sandbox implementation with seatbelt

* refactor: Remove concept of PM_CACHE

* fix: Misc fixes

* refactor: Sandbox for separation of boundaries

* fix: Apply API

* fix: Add support for sandbox cleanup

* test: Add variable interpolation test

* fix: Misc cleanup fixes

* chore: Cleanup sandbox registry

* chore: Cleanup sandbox policy

* chore: Cleanup sandbox

* fix: Misc cleanup fixes

* fix: Remove violation mode

* fix: Update config template

* chore: Go mod cleanup

* fix: Handle the case when package manager policy is explicitly disabled

* fix: Sandbox executor

* Apply suggestions from code review

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Abhisek Datta <abhisek.datta@gmail.com>

* test: Remove unused var

* test: Add test for seatbelt sandbox driver

* fix: Sandbox profile loader from file should use path for caching

* test: Add policy test

* feat: Add support for config templates

* fix: Seatbelt translator handle glob

* fix: Merge conflicts

* fix: Fix sandbox policy generator for MacOS min permissions

* fix: Sandbox path handling bugs

* fix: Deny read to dangerous directories

* fix: Deny read to dangerous directories

* add sandbox e2e (#112)

* fix: Sandbox E2E test

* fix: Code review fixes

* fix: Code review fixes

* doc: Add sandbox debugging guide

* doc: Update sandbox doc

* docs: Add sandbox usage doc

* fix: Use better error for sandbox without policy

* fix: Add sandbox for npx

* fix: Enable PTY for npm

---------

Signed-off-by: Abhisek Datta <abhisek.datta@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Sahil Bansal <bansalsahil315@gmail.com>

sandbox/profiles/README.md

@@ -0,0 +1,44 @@
+# PMG Sandbox Profiles
+
+This directory contains built-in sandbox policies for PMG package managers.
+
+## Available Profiles
+
+### npm-restrictive
+
+Restrictive policy for the npm ecosystem (npm, pnpm, yarn, bun).
+
+### pypi-restrictive
+
+Restrictive policy for the PyPI ecosystem (pip, pip3, poetry, uv).
+
+## Custom Policies
+
+You can create custom sandbox policies by:
+
+1. Copying one of the built-in profiles
+2. Modifying the rules to suit your needs
+3. Referencing the custom profile in your PMG config:
+
+```yaml
+sandbox:
+  enabled: true
+  policies:
+    npm:
+      enabled: true
+      profile: /path/to/custom-npm-policy.yml
+```
+
+## Policy Schema
+
+See the [Policy Schema Documentation](../policy.go) for details on the YAML structure.
+
+### Supported Variables
+
+- `${HOME}`: User home directory
+- `${CWD}`: Current working directory
+- `${TMPDIR}`: Temporary directory
+
+## Policy Enforcement
+
+All policy violations will block execution. This provides defense-in-depth protection against malicious install scripts and supply chain attacks.