Drop the compiler image from no-eval binaries (footprint)

An AOT-compiled app only needs the analyzer/back end at runtime to compile from
source — eval / load-string / load-file. Macros are expanded at build time and a
require of a baked namespace no-ops, so a closed app that never compiles at runtime
carries the compiler image (~0.8MB) as dead weight.

Under --tree-shake, when reachability is trustworthy (no bail) and no reachable code
references eval/load-string/load-file/load-reader/load, omit host/chez/seed/image.ss
+ compile-eval.ss from the runtime manifest. bld-tree-shake returns the flag
alongside the shaken forms; bld-emit-runtime filters the manifest.

Measured: build-app 9.84MB -> 9.05MB, still runs. Safety verified: an app that evals
keeps the compiler (eval is a bail + compile ref) and eval works at runtime.
build-smoke asserts the compiler is gone in the no-eval app; full make test green.

host/chez/emit-image.ss

@@ -117,6 +117,14 @@
     "clojure.core/load-string" "clojure.core/load-file" "clojure.core/load-reader"
     "clojure.core/load"))
 
+;; A reference that needs the analyzer/back end at runtime (compile-from-source). If
+;; reachable code uses none of these, the compiler image can be dropped from the
+;; binary — the AOT app is fully compiled. (resolve/require don't need it: resolve is
+;; a var-table lookup; a require of a baked ns no-ops.)
+(define dce-compile-refs
+  '("clojure.core/eval" "clojure.core/load-string" "clojure.core/load-file"
+    "clojure.core/load-reader" "clojure.core/load"))
+
 ;; One record per form: (vector keep? fqn refs str). keep? #t = a non-def form,
 ;; always emitted, its refs are reachability roots; #f = a prunable def emitted only
 ;; if fqn is reached. A macro is a prunable def (its expander isn't called at runtime