fix: resolve 32-bit truncation overflow in BigInt coordinate math

- Replaced 32-bit bitwise shifts (<<) with Math.pow() and BigInt shifts to support large nsides without modulo overflow.
- Recalculated compress_bits and spread_bits to explicitly loop 64-bit indexes rather than truncating with 8-bit Uint16Array table lookups (ctab/utab).
- Restored original C/C++ geographic precision boundaries allowing the engine to successfully encode and decode high-precision pixels natively up to Order 52.

package-lock.json

@@ -1,12 +1,12 @@
 {
     "name": "@gkucmierz/healpixjs-bigint",
-    "version": "1.0.0",
+    "version": "1.0.2",
     "lockfileVersion": 3,
     "requires": true,
     "packages": {
         "": {
             "name": "@gkucmierz/healpixjs-bigint",
-            "version": "1.0.0",
+            "version": "1.0.2",
             "license": "MIT"
         }
     }