Refactor GenericSegmentTree: fix formulas, add validation, expand tests (williamfiset#1251)

- Rewrite GenericSegmentTree with simplified RUF structure using 3 shared
  lambdas (addDelta, mulDelta, assignDelta) instead of 22 named fields
- Fix incorrect productQueryAssignUpdate formula (was returning d, now
  correctly returns d^count)
- Remove broken gcdQuerySumUpdate and productQuerySumUpdate RUFs
- Throw UnsupportedOperationException for GCD+ADDITION and PRODUCT+ADDITION
- Rename methods: rangeQuery1->rangeQuery, rangeUpdate1->rangeUpdate
- Delete GenericSegmentTree2 (Segment-object variant) and GenericSegmentTree3
  (commented-out pointer-based WIP) along with their tests and BUILD targets
- Expand test coverage from 14 to 38 tests including constructor validation,
  single-element arrays, edge cases, negative values, overlapping updates,
  and randomized tests for PRODUCT and MIN/MAX+MUL combos

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: williamfiset

src/main/java/com/williamfiset/algorithms/datastructures/segmenttree/BUILD

@@ -21,19 +21,6 @@ java_binary(
     runtime_deps = [":segmenttree"],
 )
 
-# bazel run //src/main/java/com/williamfiset/algorithms/datastructures/segmenttree:GenericSegmentTree2
-java_binary(
-    name = "GenericSegmentTree2",
-    main_class = "com.williamfiset.algorithms.datastructures.segmenttree.GenericSegmentTree2",
-    runtime_deps = [":segmenttree"],
-)
-
-# bazel run //src/main/java/com/williamfiset/algorithms/datastructures/segmenttree:GenericSegmentTree3
-java_binary(
-    name = "GenericSegmentTree3",
-    main_class = "com.williamfiset.algorithms.datastructures.segmenttree.GenericSegmentTree3",
-    runtime_deps = [":segmenttree"],
-)
 
 # bazel run //src/main/java/com/williamfiset/algorithms/datastructures/segmenttree:MaxQuerySumUpdateSegmentTree
 java_binary(