Add custom SVG exporter, remove Rich from screenshot rendering

- Created svg_exporter.py with direct pyte-to-SVG rendering
- Eliminates Rich's export_svg() quirks (clip path count mismatch)
- Added 63 comprehensive tests for SVG exporter
- Removed Rich imports from local_server.py, terminal_session.py,
  app_session.py, and cli.py
- Replaced RichHandler with standard logging.basicConfig
- Replaced @rich.repr.auto with standard __repr__ methods
- Rich is no longer directly imported (still transitive via textual-serve)

Bump version to 0.3.0

src/textual_webterm/cli.py

@@ -10,17 +10,15 @@ from pathlib import Path
 
 import click
 from importlib_metadata import version
-from rich.logging import RichHandler
 
 from . import constants
 from .local_server import LocalServer
 
-FORMAT = "%(message)s"
+FORMAT = "%(asctime)s %(levelname)s %(message)s"
 logging.basicConfig(
     level="DEBUG" if constants.DEBUG else "INFO",
     format=FORMAT,
-    datefmt="[%X]",
-    handlers=[RichHandler(show_path=False)],
+    datefmt="%X",
 )
 
 log = logging.getLogger("textual-webterm")