docs+cleanup: inline hot-path functions, fix stale comments

- Add `inline` to hot-path tiny functions: U256.isZero, U256.testBit,
  FieldP.reduceSelf, FieldP.neg, MutablePoint.isInfinity. These are
  called thousands of times per EC operation; inline eliminates virtual
  call overhead (mostly helps Kotlin/Native; JVM JIT already inlines).
- Fix stale comment: G_TABLE_SIZE is 1024 for w=12 (was "64 for w=8")

https://claude.ai/code/session_01BhU63WUe9AhikZxRdw3Lpg

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/secp256k1/FieldP.kt

@@ -132,7 +132,7 @@ internal object FieldP {
         reduceWide(out, w)
     }
 
-    fun neg(
+    inline fun neg(
         out: LongArray,
         a: LongArray,
     ) {
@@ -298,7 +298,7 @@ internal object FieldP {
 
     // ==================== Reduction ====================
 
-    fun reduceSelf(a: LongArray) {
+    inline fun reduceSelf(a: LongArray) {
         // Exploit P's structure: P = [P0, -1, -1, -1] where P[1..3] = 0xFFFFFFFFFFFFFFFF.
         // a >= P only if a[3]==a[2]==a[1]==-1 AND a[0] >= P[0]. The first check (a[3]==-1)
         // fails >99.99% of the time for random field elements, making this a single branch.

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/secp256k1/Point.kt

@@ -93,7 +93,7 @@ internal class MutablePoint(
     val y: LongArray = LongArray(4),
     val z: LongArray = LongArray(4),
 ) {
-    fun isInfinity(): Boolean = U256.isZero(z)
+    inline fun isInfinity(): Boolean = U256.isZero(z)
 
     fun setInfinity() {
         for (i in 0 until 4) {
@@ -163,7 +163,7 @@ internal object ECPoint {
      * w=12 is a good tradeoff for runtime-computed tables on JVM.
      */
     private const val WINDOW_G = 12
-    private val G_TABLE_SIZE = 1 shl (WINDOW_G - 2) // 64 for w=8
+    private val G_TABLE_SIZE = 1 shl (WINDOW_G - 2) // 1024 for w=12
 
     /**
      * Precomputed G odd-multiples for wNAF: gOddTable[i] = (2i+1)·G as affine, for i in 0..G_TABLE_SIZE-1.

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/secp256k1/U256.kt

@@ -51,7 +51,7 @@ package com.vitorpamplona.quartz.utils.secp256k1
 internal object U256 {
     val ZERO = LongArray(4)
 
-    fun isZero(a: LongArray): Boolean = (a[0] or a[1] or a[2] or a[3]) == 0L
+    inline fun isZero(a: LongArray): Boolean = (a[0] or a[1] or a[2] or a[3]) == 0L
 
     /** Unsigned comparison. Returns -1 if a < b, 0 if equal, 1 if a > b. */
     fun cmp(
@@ -253,8 +253,8 @@ internal object U256 {
         return ((a[limb] ushr shift) and 0xF).toInt()
     }
 
-    /** Test if bit at position pos is set. */
-    fun testBit(
+    /** Test if bit at position pos is set. Called ~2,800× per mulG (comb table lookup). */
+    inline fun testBit(
         a: LongArray,
         pos: Int,
     ): Boolean = (a[pos / 64] ushr (pos % 64)) and 1L == 1L