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/chat.py

@@ -0,0 +1,128 @@
+"""
+Chat command - interactive conversation mode.
+"""
+import asyncio
+from pathlib import Path
+
+import typer
+
+from src.cli.theme import get_theme
+from src.cli.ui.console import get_console
+from src.cli.session.loop import AgenticLoop
+from src.shared.logging import setup_logging
+
+console = get_console()
+
+
+def chat_command(
+    directory: str = typer.Option(
+        ".",
+        "--directory",
+        "-d",
+        help="Working directory to explore",
+    ),
+    verbose: bool = typer.Option(
+        False,
+        "--verbose",
+        "-V",
+        help="Show detailed output and debug logging",
+    ),
+) -> None:
+    """
+    Start interactive chat session.
+
+    Enters a conversation loop where you can ask questions about the codebase.
+    The explore agent will search files, read code, and answer questions.
+
+    Examples:
+        webber chat
+        webber chat -d ./src
+        webber chat --verbose
+    """
+    # Set up logging
+    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)
+
+    # Run the async chat loop
+    try:
+        asyncio.run(_chat_loop(working_dir, verbose))
+    except KeyboardInterrupt:
+        console.print("\n[dim]Goodbye![/]")
+
+
+async def _chat_loop(working_dir: str, verbose: bool) -> None:
+    """Async chat loop implementation."""
+    from src.domains.agents.explore import explore_agent
+
+    # Create the agentic loop
+    loop = AgenticLoop(
+        agent=explore_agent,
+        console=console,
+        working_dir=working_dir,
+    )
+
+    # Display welcome
+    loop.display_welcome()
+
+    # Main conversation loop
+    while True:
+        try:
+            # Get user input
+            user_input = console.input("[prompt]>[/] ").strip()
+
+            # Handle special commands
+            if not user_input:
+                continue
+
+            if user_input.lower() in ("exit", "quit", "/exit", "/quit"):
+                console.print("[dim]Goodbye![/]")
+                break
+
+            if user_input.lower() in ("clear", "/clear"):
+                loop.state.clear_history()
+                console.print("[info]History cleared.[/]")
+                continue
+
+            if user_input.lower() in ("status", "/status"):
+                loop.display_status()
+                continue
+
+            if user_input.lower().startswith("cd "):
+                new_dir = user_input[3:].strip()
+                new_path = Path(new_dir).resolve()
+                if new_path.exists() and new_path.is_dir():
+                    loop.set_working_dir(str(new_path))
+                else:
+                    console.print(f"[error]Directory not found:[/] {new_dir}")
+                continue
+
+            # Process with agent
+            theme = get_theme()
+            with console.status("[info]Thinking...[/]", spinner=theme.spinner):
+                response = await loop.run_turn(user_input)
+
+            # Display response
+            console.print()
+            loop.display_response(response)
+            console.print()
+
+        except KeyboardInterrupt:
+            console.print("\n[dim]Use 'exit' to quit or press Ctrl+C again.[/]")
+            try:
+                # Wait briefly for second Ctrl+C
+                await asyncio.sleep(0.5)
+            except KeyboardInterrupt:
+                console.print("\n[dim]Goodbye![/]")
+                break
+
+        except Exception as e:
+            console.print(f"[error]Error:[/] {e}")
+            if verbose:
+                console.print_exception()