README: two explicit install paths; Windows launchers pass --db and quote paths

- the Install section now leads with the release artifacts (the wheel via
  pipx/pip, the direct release URL, `gh release download` for the
  version-agnostic case, and the source archive) and keeps the git clone as
  the development path.  It finally names the launchers (./start.sh,
  start.bat): a clone needs no install, but the README never said how to start
  it while the Running section only showed the console script that an install
  provides.
- Windows: the USB section now says the .bat launchers mirror the shell ones
  and call the `python` command (Python 3 must be on PATH); the Install section
  carries the same note.
- start.bat: --db/DB was parsed and then never passed to the server; it is
  passed now, and --gsmtap-port is sent only for gsmtap capture (as start.sh
  already did).  Both .bat files passed values unquoted and stripped the
  quotes of pass-through options, so paths with spaces broke
  (--db "C:\My Data\...", --web-dir, --pcap, --output); values are quoted now
  and pass-through keeps the original quoting (argument assembly through
  delayed expansion).
- the launcher usage comments include the `disabled` capture mode.
- verified the argument assembly with Wine cmd.exe and an echo harness: the
  quoted paths survive, --db arrives, --gsmtap-port appears only for gsmtap;
  547 Python + 80 Node tests.

start.bat

@@ -3,7 +3,7 @@ setlocal enabledelayedexpansion
 
 :: simtrace-analyser-server startup script for Windows
 ::
-:: Usage: start.bat [--capture gsmtap|direct] [--port PORT] [--db PATH] [--gsmtap-port PORT]
+:: Usage: start.bat [--capture gsmtap|direct|disabled] [--port PORT] [--db PATH] [--gsmtap-port PORT]
 ::
 :: Options set via environment variables act as defaults; CLI flags override them.
 
@@ -42,7 +42,7 @@ if "%~1"=="--gsmtap-port" (
     shift
     goto :parse_args
 )
-set "EXTRA_ARGS=!EXTRA_ARGS! %~1"
+set "EXTRA_ARGS=!EXTRA_ARGS! %1"
 shift
 goto :parse_args
 
@@ -50,5 +50,10 @@ goto :parse_args
 echo Starting simtrace-analyser-server...
 echo PWA (simtrace-analyser) will be served at http://127.0.0.1:%PORT%/
 
+set "ARGS=--capture "%CAPTURE%" --port "%PORT%""
+if not "%DB%"=="" set "ARGS=!ARGS! --db "%DB%""
+if /i "%CAPTURE%"=="gsmtap" set "ARGS=!ARGS! --gsmtap-port "%GSMTAP_PORT%""
+set "ARGS=!ARGS! !EXTRA_ARGS!"
+
 set "PYTHONPATH=%~dp0"
-python -m simtrace_analyser --capture %CAPTURE% --port %PORT% --gsmtap-port %GSMTAP_PORT% %EXTRA_ARGS%
+python -m simtrace_analyser !ARGS!