ysync 0009 phase 4: sym_convert --lint mode (kicad_lint folded into the converter)

sym_convert --lint [--strict] <file...>: full parse for .kicad_sch (restored
LoadSchematicFile + minimal headless PGM/SETTINGS_MANAGER runtime,
aSetActive=false) and .kicad_sym/.lib; structure-only for other s-expr files;
dup-uuid identity lints (walker) on every s-expr input; errors as
file:line:offset, exit 0/1/2. Convert mode byte-identical (qa gate).

Fixes en route: 64KB stack local overflowed the default wasm stack (mimalloc
corruption); pre-js now inherits process.env into getenv (KICAD_CONFIG_HOME /
SYM_CONVERT_TRACE); font abort stub retired (SCH_SCREEN::Append bbox resolves
draw fonts) -> 18.0MB; six GetMsgPanelInfo typeinfo stubs; BUILD_3D_VIEWER
defaults OFF for headless CLIs (gl1 shim needs glm).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0142yAmMGZ3Ejrq3wwVr2Yq2

docker/build.sh

@@ -237,8 +237,11 @@ compile_app() {
     # -e EMSDK=/emsdk: `docker compose exec` bypasses the entrypoint that sources
     # emsdk_env.sh, so the build shell would lack emcc/embuilder on PATH. Setting
     # EMSDK lets scripts/common/env.sh source /emsdk/emsdk_env.sh and activate the toolchain.
+    # BUILD_3D_VIEWER passes through EMPTY when the host didn't set it, so
+    # build-kicad-target.sh can apply per-app defaults (ON for editors, OFF
+    # for headless CLIs like sym_convert — the gl1 shim needs glm).
     docker compose -f docker/docker-compose.yml exec -e EMSDK=/emsdk \
-        -e BUILD_3D_VIEWER="${BUILD_3D_VIEWER:-ON}" \
+        -e BUILD_3D_VIEWER="${BUILD_3D_VIEWER:-}" \
         kicad-wasm-builder \
         "/workspace/scripts/kicad/build-${app}.sh" "${ARGS[@]}"