refactor: reorganize into monorepo with separate subprojects

Structure webber into three independent subprojects:
- webber-api/: FastAPI backend server with all agent code
- webber-cli/: Standalone CLI client (renamed from cli/ to webber_cli/)
- webber-sandbox/: Test project for functional testing

Key changes:
- Each subproject has its own .venv (Python 3.12+)
- Added sandbox.sh for managing test project templates
- Created sandbox-templates/ with calculator-cli and empty starter
- Updated CI/CD for prefixed tags (api/v*, cli/v*)
- Added comprehensive AGENTS.md with operational instructions
- Added gitignore filtering to glob and grep tools
- Created pyproject.toml for each subproject

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

sandbox-templates/calculator-cli/src/calculator/__init__.py

@@ -0,0 +1,3 @@
+"""Calculator CLI - A simple calculator with some bugs for testing."""
+
+__version__ = "0.1.0"

sandbox-templates/calculator-cli/src/calculator/main.py

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+#!/usr/bin/env python3
+"""
+Calculator CLI - A simple command-line calculator.
+
+NOTE: This file contains intentional bugs for testing purposes.
+
+Usage:
+    python -m calculator.main 10 5 add
+    python -m calculator.main 10 5 sub
+    python -m calculator.main 10 5 mul
+    python -m calculator.main 10 5 div
+"""
+import sys
+
+from calculator.operations import add, subtract, multiply, divide
+
+
+def get_operation(op_name: str):
+    """
+    Get the operation function by name.
+
+    BUG: No validation - invalid operation names cause KeyError!
+    """
+    operations = {
+        "add": add,
+        "sub": subtract,
+        "mul": multiply,
+        "div": divide,
+        # BUG: 'power' is implemented in operations.py but not exposed here
+    }
+    # BUG: Should handle KeyError gracefully
+    return operations[op_name]
+
+
+def main():
+    """Main entry point."""
+    if len(sys.argv) != 4:
+        print("Usage: python -m calculator.main <a> <b> <operation>")
+        print("Operations: add, sub, mul, div")
+        sys.exit(1)
+
+    # BUG: No validation that a and b are valid numbers
+    a = float(sys.argv[1])
+    b = float(sys.argv[2])
+    op_name = sys.argv[3]
+
+    # BUG: This will crash with KeyError for invalid operation
+    operation = get_operation(op_name)
+    result = operation(a, b)
+
+    print(f"Result: {result}")
+
+
+if __name__ == "__main__":
+    main()

sandbox-templates/calculator-cli/src/calculator/operations.py

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+"""
+Math operations for the calculator.
+
+NOTE: This file contains intentional bugs for testing purposes.
+"""
+
+
+def add(a: float, b: float) -> float:
+    """Add two numbers."""
+    return a + b
+
+
+def subtract(a: float, b: float) -> float:
+    """Subtract b from a."""
+    return a - b
+
+
+def multiply(a: float, b: float) -> float:
+    """Multiply two numbers."""
+    return a * b
+
+
+def divide(a: float, b: float) -> float:
+    """
+    Divide a by b.
+
+    BUG: Does not handle division by zero!
+    """
+    # BUG: No check for b == 0
+    return a / b
+
+
+def power(a: float, b: float) -> float:
+    """
+    Raise a to the power of b.
+
+    BUG: Negative exponents not handled correctly for some cases.
+    """
+    # BUG: This naive implementation has issues with negative bases and fractional exponents
+    result = 1
+    for _ in range(int(b)):
+        result *= a
+    return result