haskell: fix string ↔ [Char] equality — palindrome 12/12, conformance 34/34 (269/269)

Haskell strings are [Char]. Calling reverse / head / length on a SX raw
string transparently produces a cons-list of char codes (via hk-str-head /
hk-str-tail in runtime.sx), but (==) then compared the original raw string
against the char-code cons-list and always returned False — so
"racecar" == reverse "racecar" was False.

Added hk-try-charlist-to-string and hk-normalize-for-eq in eval.sx; routed
== and /= through hk-normalize-for-eq so a string compares equal to any
cons-list whose elements are valid Unicode code points spelling the same
characters, and "[]" ↔ "".

palindrome.hs lifts from 9/12 → 12/12; conformance 33/34 → 34/34 programs,
266/269 → 269/269 tests.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/haskell/scoreboard.json

@@ -1,7 +1,7 @@
 {
   "date": "2026-05-07",
-  "total_pass": 266,
-  "total_fail": 3,
+  "total_pass": 269,
+  "total_fail": 0,
   "programs": {
     "fib": {"pass": 2, "fail": 0},
     "sieve": {"pass": 2, "fail": 0},
@@ -9,7 +9,7 @@
     "nqueens": {"pass": 2, "fail": 0},
     "calculator": {"pass": 5, "fail": 0},
     "collatz": {"pass": 11, "fail": 0},
-    "palindrome": {"pass": 9, "fail": 3},
+    "palindrome": {"pass": 12, "fail": 0},
     "maybe": {"pass": 12, "fail": 0},
     "fizzbuzz": {"pass": 12, "fail": 0},
     "anagram": {"pass": 9, "fail": 0},