feat(libs): standalone .lib→.kicad_sym wasm converter (sym_convert)

Headless node-WASM CLI that converts legacy symbol libraries to .kicad_sym via
SCH_IO_MGR::ConvertLibrary. Adds wasm/cli/sym_convert_main.cpp + sym_convert_pre.js
(in-memory localStorage + wxConfig JS-hook shim), registers sym_convert as a
docker/build.sh app (own kicad-sym_convert tree, real wasm-opt/finalize in-container,
skip host postprocess), and bumps the kicad pointer for the matching target.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

wasm/cli/sym_convert_main.cpp

@@ -0,0 +1,61 @@
+/*
+ * sym_convert — standalone CLI for legacy (.lib) -> S-expression (.kicad_sym)
+ * symbol-library conversion, built as a WebAssembly module.
+ *
+ * It drives SCH_IO_MGR::ConvertLibrary directly from main(): no GUI, no
+ * renderer, no embind bindings, no JS host logic. Wired into
+ * eeschema/CMakeLists.txt behind the KICAD_SYM_CONVERTER_WASM option
+ * (see scripts/kicad/build-sym-convert-wasm.sh).
+ *
+ * Targets:
+ *   - Node:     built with -sENVIRONMENT=node -sNODERAWFS=1 (the default here);
+ *               run with `node sym_convert.js in.lib out.kicad_sym`.
+ *   - wasmtime: a follow-up build (no pthreads, -sSTANDALONE_WASM) lets the
+ *               same code run host-less under `wasmtime sym_convert.wasm ...`.
+ *
+ * GPL note: this is GPL KiCad code. The artifact is meant to be invoked as a
+ * separate process from the closed ingester, never linked into closed code.
+ */
+
+#include <cstdio>
+
+#include <wx/init.h>
+#include <wx/string.h>
+
+#include <sch_io/sch_io_mgr.h>
+
+int main( int argc, char** argv )
+{
+    if( argc < 3 )
+    {
+        std::fprintf( stderr, "usage: sym_convert <input.lib> <output.kicad_sym>\n" );
+        return 2;
+    }
+
+    // Bring up wxBase (no GUI): wxString / wxFileName / wxFFile rely on the
+    // library being initialised. If the conversion path turns out to need more
+    // global state (PGM_BASE, settings), the run will surface it here.
+    wxInitializer initializer( argc, argv );
+
+    if( !initializer.IsOk() )
+    {
+        std::fprintf( stderr, "sym_convert: wxWidgets initialisation failed\n" );
+        return 3;
+    }
+
+    const wxString inPath  = wxString::FromUTF8( argv[1] );
+    const wxString outPath = wxString::FromUTF8( argv[2] );
+
+    // aOldFileProps = nullptr: no library-table properties; ConvertLibrary
+    // guesses the source format from the path and writes the SCH_KICAD format.
+    const bool ok = SCH_IO_MGR::ConvertLibrary( nullptr, inPath, outPath );
+
+    if( ok )
+    {
+        std::fprintf( stderr, "sym_convert: OK  %s -> %s\n", argv[1], argv[2] );
+        return 0;
+    }
+
+    std::fprintf( stderr, "sym_convert: FAILED to convert %s\n", argv[1] );
+    return 1;
+}