Replace all references from docs.scipy.org/doc/numpy to numpy.org/doc/stable
across 125 C# source files.

The old docs.scipy.org URLs (both unversioned and version-pinned numpy-1.14
through numpy-1.17) now redirect or return 404. The canonical NumPy
documentation is at numpy.org/doc/stable/.

Fixes SciSharp#530

Updates URLs that were pointing to incorrect paths:

1. Random functions (12 URLs): Added /random/ directory
   - reference/generated/numpy.random.* → reference/random/generated/numpy.random.*

2. arrays.indexing (1 URL): Corrected section path
   - reference/arrays.indexing.html → user/basics.indexing.html

3. c-api.dtype (1 URL): Fixed path format
   - reference/c-api.dtype.html → reference/c-api/dtype.html

4. routines.random (1 URL): Updated to new location
   - reference/routines.random.html → reference/random/index.html

5. asscalar (6 URLs): Function removed in NumPy 1.23, now links to replacement
   - numpy.asscalar.html → numpy.ndarray.item.html

6. find_common_type (6 URLs): Function deprecated, now links to replacement
   - numpy.find_common_type.html → numpy.result_type.html

7. itemset (4 URLs): Function removed in NumPy 2.4, now links to alternative
   - numpy.ndarray.itemset.html → numpy.put.html

All 126 URLs now return HTTP 200.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>