set up the skeletal structure for comp, gate, denoiser

add them as subcommand to the strip command group.

for each one implement one or two subcommands.

src/vban_cli/comp.py

@@ -0,0 +1,67 @@
+from typing import Annotated
+
+from cyclopts import App, Argument, Parameter
+
+from .context import Context
+from .help import CustomHelpFormatter
+
+app = App(name='comp', help_formatter=CustomHelpFormatter())
+
+
+@app.meta.default
+def launcher(
+    *tokens: Annotated[str, Parameter(show=False, allow_leading_hyphen=True)],
+    index: Annotated[int, Argument()] = None,
+    ctx: Annotated[Context, Parameter(show=False)] = None,
+):
+    """Control the compressor parameters."""
+    additional_kwargs = {}
+    command, bound, _ = app.parse_args(tokens)
+    if index is not None:
+        additional_kwargs['index'] = index
+    if ctx is not None:
+        additional_kwargs['ctx'] = ctx
+
+    return command(*bound.args, **bound.kwargs, **additional_kwargs)
+
+
+@app.command(name='knob')
+def knob(
+    new_knob: Annotated[float, Argument()] = None,
+    *,
+    index: Annotated[int, Parameter(show=False)] = None,
+    ctx: Annotated[Context, Parameter(show=False)] = None,
+):
+    """Get or set the knob of the specified compressor.
+
+    Parameters
+    ----------
+    new_knob : int, optional
+        If provided, sets the knob to this value. If not provided, the current knob is printed.
+    """
+    if new_knob is None:
+        # See https://github.com/onyx-and-iris/vban-cli?tab=readme-ov-file#implementation-notes - 2.
+        # console.out.print(ctx.client.strip[index].comp.knob)
+        return
+    ctx.client.strip[index].comp.knob = new_knob
+
+
+@app.command(name='input-gain')
+def input_gain(
+    new_gain: Annotated[float, Argument()] = None,
+    *,
+    index: Annotated[int, Parameter(show=False)] = None,
+    ctx: Annotated[Context, Parameter(show=False)] = None,
+):
+    """Get or set the input gain of the specified compressor.
+
+    Parameters
+    ----------
+    new_gain : float, optional
+        If provided, sets the input gain to this value. If not provided, the current input gain is printed.
+    """
+    if new_gain is None:
+        # See https://github.com/onyx-and-iris/vban-cli?tab=readme-ov-file#implementation-notes - 2.
+        # console.out.print(ctx.client.strip[index].comp.gainin)
+        return
+    ctx.client.strip[index].comp.gainin = new_gain