fix(lmao): resolve trace-preload packages dir from consumer cwd

The bun trace preload anchored workspace resolution on the library's
own location (published 0.2.2: import.meta.dir walk-up; HEAD: a probe
for packages/lmao/package.json). Both fail when lmao is an installed
dependency of a foreign workspace — under Bun's isolated store
the walk lands in node_modules, tracing silently never installs,
and consumer .trace-results.db databases go stale unnoticed.

Resolution now walks up from process.cwd() to the nearest bun.lock/
bun.lockb ancestor with a packages/ directory (nested lockfiles
without one are walked past), with LMAO_PACKAGES_DIR as the explicit
override for nonstandard layouts. The preload is wiring-only; failure
to resolve prints a stderr line naming the searched paths and the
override — disabled tracing must never be a silent no-op.