Recursive `self` not bound during DAG β-reduction

[protocolstardust]

A lambda that calls itself via self evaluates correctly at the top level but fails with error: domain when applied to a column inside select. The DAG's named-lambda inliner treats self as a free variable instead of as a binding to the enclosing lambda.

Reproduction

Reproduced against ~/rayforce head, commit b3e7bdb3.

;; Define a recursive Fibonacci using `self`.
(set fib (fn [x] (if (< x 2) 1 (+ (self (- x 1)) (self (- x 2))))))

;; Direct application — works.
(println (fib 5))           ;; => 8

;; The same lambda inside select against a column — fails.
(set t (table [n] (list (til 6))))
(println (select [n (fib n)] from t))
;; => error: domain

Expected behavior

(select [n (fib n)] from t) should produce a 2-column table where the
second column is [1 1 2 3 5 8] — the per-row application of fib.

The DAG β-reducer must bind self to the lambda being inlined, the same way
direct evaluation does, so a recursive lambda passed into a column expression
behaves identically to one called directly.

[singaraiona]

Fixed in e98f7cd.

select projection now falls back to row-wise evaluation when an expression cannot be lowered into the query DAG. That preserves the normal evaluator environment, including recursive self binding, so recursive lambdas such as the reported fib case work inside projected select expressions.

Added regression coverage for (fib n) over a table column.

Verification: make test passes with 2348/2349 passing, 1 skipped, 0 failed.