reflective: Tcl adapter cfg — second consumer wired, 427+322 tests green

Phase 2 of the lib-guest-reflective extraction.

lib/tcl/runtime.sx — frame-lookup and frame-set-top now delegate to
refl-env-lookup-or-nil-with and refl-env-bind!-with via a new
tcl-frame-cfg adapter. Tcl keeps its existing {:level :locals :parent}
frame shape unchanged; the cfg bridges it to the kit's generic
algorithms. Functional update semantics preserved (cfg's :bind!
returns the new frame via assoc).

lib/tcl/test.sh + conformance.sh — load lib/guest/reflective/env.sx
before lib/tcl/runtime.sx.

Both consumers' full test suites unchanged:
- Tcl: 427/427 (parse 67, eval 169, error 39, namespace 22, coro 20,
       idiom 110)
- Kernel: 322/322 across 7 suites

The extraction is now real: two consumers, two genuinely different
wire shapes (mutable canonical vs functional frame), sharing the
parent-walk algorithm via cfg adapter — same pattern as
lib/guest/match.sx.

lib/tcl/test.sh

@@ -42,6 +42,7 @@ cat > "$TMPFILE" << EPOCHS
 (load "lib/tcl/tests/parse.sx")
 (epoch 4)
 (load "lib/fiber.sx")
+(load "lib/guest/reflective/env.sx")
 (load "lib/tcl/runtime.sx")
 (epoch 5)
 (load "lib/tcl/tests/eval.sx")