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.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 # simtrace-analyser-server startup script
 #
-# Usage: ./start.sh [--capture gsmtap|direct] [--port PORT] [--db PATH] [--gsmtap-port PORT]
+# Usage: ./start.sh [--capture gsmtap|direct|disabled] [--port PORT] [--db PATH] [--gsmtap-port PORT]
 #
 # Options set via environment variables act as defaults; CLI flags override them.