docs(wasm-gui): M8 — debug tools first, unmodified-upstream constraint #5, commit to openbox

Per direction: (1) reorder so the out-of-band debugging toolchain is the first M8 milestone
(M8.1) before any DE component, since the spike cost multiple sessions for lack of native
observability; (2) add constraint #5 — DE/X/GTK components build+run from UNMODIFIED upstream
source, fixes go in the native/platform layer (runtime/sidecar/VFS/X-server + toolchain
sysroot/shim), never in the component source (flag the M8.0 per-lib X edits as a deviation to
repay in the libc pthread layer); (3) commit firmly to real LXDE with real openbox, no
JWM/twm substitute. Renumbered: M8.1 tools -> M8.2 openbox -> M8.3 menu-cache/libfm ->
M8.4 lxpanel -> M8.5 pcmanfm -> M8.6 session = acceptance. Reframed dbus/dlopen/volume/SVG
items as native-or-config rather than source/build edits.

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

Author: NathanFlurry