refactor(bridge): split fx bridge, stabilize VST3 host chain, drop old install engines

- remove diagnostic canaries from audio hot path (crackle fix) and
  stuck C5 note raw-MIDI test (Vst2Instrument::init noteOff)
- split native bridge into daw_vst_bridge (VSTi) + fx_vst_bridge (VST FX)
- VST3: processData prepare before setActive, zero input buses, accept
  both .vstpreset and bridge-state blob in RenderJob presets
- native_render/vst_engine: bridge-exe discovery + render_fx_chain + /fx-gui
- delete old install/ engine binaries (install via sidecar+resources now)
- add BUILD_LAYOUT.md, build_selfcheck, tools/ diagnostics

package-lock.json

@@ -700,9 +700,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [
@@ -720,9 +717,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [
@@ -740,9 +734,6 @@
         "riscv64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [
@@ -760,9 +751,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [
@@ -780,9 +768,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [