Add make install for global sandboxer CLI

Document uv tool install path and uv run fallback so sandboxer is
available outside the project venv after make install.

.claude/rules/stack-and-commands.md

@@ -13,6 +13,13 @@ Run from the repo root. First-time setup:
 
 ```bash
 make setup          # uv sync --all-groups → .venv
+make install        # sandboxer → ~/.local/bin (ensure ~/.local/bin is on PATH)
+```
+
+Without global install, prefix commands with `uv run` from the repo root:
+
+```bash
+uv run sandboxer create --profile profile.compose-e2e --input repo=/path/to/repo
 ```
 
 Day-to-day verification (run before committing):

AGENTS.md

@@ -165,6 +165,7 @@ get wrong.
 
 ```bash
 make setup          # install deps into .venv
+make install        # sandboxer CLI → ~/.local/bin (add to PATH if needed)
 make check          # lint + test — run before committing
 make test           # pytest
 make lint           # ruff check

Makefile

@@ -1,6 +1,6 @@
 .DEFAULT_GOAL := help
 
-.PHONY: help setup test lint format build check cli-version
+.PHONY: help setup install test lint format build check cli-version
 
 help: ## List available make targets
 	@awk 'BEGIN {FS = ":.*## "}; /^[a-zA-Z0-9_.-]+:.*## / {printf "  %-16s %s\n", $$1, $$2}' $(MAKEFILE_LIST)
@@ -8,6 +8,9 @@ help: ## List available make targets
 setup: ## Sync dependencies into .venv
 	uv sync --all-groups
 
+install: ## Install sandboxer CLI to ~/.local/bin (editable)
+	uv tool install -e . --force
+
 test: ## Run the test suite
 	uv run pytest