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>

webber-api/src/cli/commands/explore.py

@@ -0,0 +1,83 @@
+"""
+Explore command - one-shot codebase exploration.
+"""
+import asyncio
+from pathlib import Path
+
+import typer
+from rich.panel import Panel
+
+from src.cli.theme import get_theme
+from src.cli.ui.console import get_console
+from src.cli.ui.display import format_response
+from src.shared.logging import setup_logging
+
+console = get_console()
+
+
+def explore_command(
+    query: str = typer.Argument(..., help="What to search for in the codebase"),
+    directory: str = typer.Option(
+        ".",
+        "--directory",
+        "-d",
+        help="Working directory to explore",
+    ),
+    verbose: bool = typer.Option(
+        False,
+        "--verbose",
+        "-V",
+        help="Show detailed output",
+    ),
+) -> None:
+    """
+    One-shot codebase exploration.
+
+    Searches the codebase for the given query and returns findings.
+
+    Examples:
+        webber explore "where is config loaded"
+        webber explore "find all API endpoints" -d ./src
+        webber explore "how does authentication work"
+    """
+    # Set up logging based on verbosity
+    log_level = "DEBUG" if verbose else "WARNING"
+    setup_logging(log_level)
+
+    # Resolve directory
+    working_dir = str(Path(directory).resolve())
+
+    if not Path(working_dir).exists():
+        console.print(f"[error]Error:[/] Directory not found: {working_dir}")
+        raise typer.Exit(1)
+
+    console.print(f"[dim]Exploring:[/] [path]{working_dir}[/]")
+    console.print(f"[dim]Query:[/] {query}\n")
+
+    # Run the exploration
+    asyncio.run(_explore_async(query, working_dir, verbose))
+
+
+async def _explore_async(query: str, working_dir: str, verbose: bool) -> None:
+    """Async exploration implementation."""
+    from src.domains.agents.explore import explore
+
+    theme = get_theme()
+
+    try:
+        with console.status("[info]Searching codebase...[/]", spinner=theme.spinner):
+            result = await explore(query, working_dir=working_dir)
+
+        # Display result
+        formatted = format_response(result)
+        console.print(Panel(
+            formatted,
+            title="[success]Findings[/]",
+            border_style=theme.colors.border_success,
+        ))
+
+    except Exception as e:
+        console.print(f"[error]Error:[/] {e}")
+        if verbose:
+            console.print_exception()
+        raise typer.Exit(1)