fix: threaded HTTP server so the RAM modal progress is live (v3.6.39)

__main__ built a plain HTTPServer (single-threaded): during a RAM install
POST every other request waited in the accept queue, including the 2 s
/api/status poll that feeds the operation modal - its bar and step
headline never moved and the whole result appeared only at the end (live
2026-09-29).

_build_http_server() now returns a ThreadingHTTPServer (daemon threads).
Card access is unchanged: it is serialized by _CARD_LOCK, not by the
server - every POST is blanket-wrapped in do_POST, every /api/ GET except
/api/status and /api/test/status is wrapped in do_GET, and the background
threads (STATUS poll, _bip_data_available, test runner) take the lock;
the audit found no card-access holes.  do_GET also lets non-/api (static
PWA) paths bypass the lock, so page assets stay answerable during long
operations.

Regression test tests/test_http_concurrency.py: a fast request must
complete while a slow one is in flight (fails on HTTPServer with exactly
the reported symptom: 1.01 s vs 0.20 s); test_startup_cardless patches
the new factory.

sw cache simple-v312; tests: 519 Python / 674 Node.

pysim_simple_server/__main__.py

@@ -4,7 +4,7 @@ import os
 import sys
 import time
 import traceback
-from http.server import HTTPServer
+from http.server import ThreadingHTTPServer
 from pySim.card_handler import CardHandler
 from pySim.commands import SimCardCommands
 from pySim.exceptions import NoCardError
@@ -37,6 +37,19 @@ def _default_mcc_mnc_list():
     return os.path.join(pkg, 'data', 'mcc-mnc-list.json')
 
 
+def _build_http_server(host, port, handler):
+    """HTTP server for the PWA + API.
+
+    Threaded on purpose: card access is serialized by ``_CARD_LOCK`` (all
+    POSTs, the card-touching GETs and the background threads take it), so
+    while a long operation holds the lock the cached endpoints and static
+    files must still be answerable - a single-threaded server starved the
+    RAM modal's live progress poll (`/api/status.ram_progress`) and showed
+    the whole install result only at the end.  Daemon threads keep a stuck
+    request from blocking shutdown."""
+    return ThreadingHTTPServer((host, port), handler)
+
+
 def main():
     global _server_start
     _server_start = time.time()
@@ -247,7 +260,7 @@ def main():
             orig_onchange(param_name, old, new)
             _reattach_tracer()
         app._onchange_apdu_trace = _onchange_apdu_trace
-    server = HTTPServer((opts.http_host, opts.http_port), PysimHandler)
+    server = _build_http_server(opts.http_host, opts.http_port, PysimHandler)
     server.sl = sl
     server.scc = scc
     server.card = card