The driver flip moves build artifacts from next-to-source <stem>.s to a
.sepwork/ scratch dir. 29 Pattern-B gates now build `ww build --sep -o <stem>`
and read <stem>.sepwork/__root.s (multi-package gates concat all
<stem>.sepwork/*.s, since cross-package labels live in per-package .s).
All intermediates redirect to /tmp (WW_PKGCACHE + -o), so the corpus runs
parallel-safe with no source-tree pollution. Tests pass now (--sep is live)
and survive the flip.
915 additionally retargeted off strconv's PRIVATE left_shift_table (a let,
not export) — which separate compilation correctly hides — onto a test-local
package that exports its own probe table (#96). The combined path only linked
it via a single-unit private leak; encapsulation is now honored under sep.
Test-only; all 5 *_ww binaries HOLD. 989_m1mangle_run deferred (blocked by
#99, imported-package fn main mangling under sep).
use_hint/usehint were unit-global first-leaf-match: two directory-
packages exporting the same fn leaf, each imported by a different module
aliasing the same bareword, mis-routed every qualified call to whichever
use was collected first. Identically wrong on both stages (byte-id-green
#263-class). Key the hint on (owner-module, alias) and prefer cur_mod,
mirroring the checker's use_path curmod-preference (55f54fb).
989_m1usehint_run: two same-leaf pick() across a.math/b.math, each
module's call routes to its own import (111/222) + cs.s==ww.s.
