Address findings from code-reviewer + debugger-assistant +
refactor-specialist multi-review on 8e1c47ebc2:
- afterPack: read wrapper source before rename; on writeFile failure,
roll the rename back so a broken intermediate state can't ship a
package with no launcher. Strengthen idempotency check to require a
shebang at binPath (both files alone no longer counts as "installed").
- wrapper: gate the X11 injection on \$SNAP_NAME = "superproductivity",
not just \$SNAP set. An xdg-open from a sibling snap (e.g. Firefox)
leaks \$SNAP into the child env, which previously would have silently
forced XWayland on .deb/.rpm users. Derive BIN_DIR from \$SNAP
directly when we are our snap, avoiding fragile \$0 resolution
through snapd's wrapper chain. Stop argv scanning at -- so positional
args that resemble --ozone-platform aren't misread as a user override.
- app-control: point app.relaunch() execPath at the sibling shell
wrapper instead of the default process.execPath (which is the renamed
ELF and would bypass the flag injection on a relaunched Snap+Wayland
instance).
- Move build/snap-wrapper.sh -> build/linux/snap-wrapper.sh to match
the existing build/linux/ layout convention.
- Update research doc §18 to reflect the tightened predicate and the
relaunch fix.
