chore: native ANN vector index on the Tensors stack; drop external FaissNet

Replaces the broken external FaissNet backend (its IVF/PQ path dies with a
process-fatal "Cannot load mkl_def.2.dll") with a dependency-free native ANN
index built on AiDotNet.Tensors' fused ANN kernels.

- AnnVectorIndex<T> : IVectorIndex<T> — Flat/IVF/PQ/IVFPQ over Tensors' AnnIndex.
  Bridges the incremental Add/Remove/Search index contract onto a train-then-
  populate ANN index via a live-vector source of truth + lazy rebuild, and
  AttachGpu() dispatches to the fused GPU ANN kernels across all 7 backends,
  falling back to the managed CPU reference. Reuses the existing
  VectorIndexDocumentStore adapter, so it plugs into the RAG facade unchanged.
- AiModelBuilder.ConfigureNativeAnnIndex(...) (on both IAiModelBuilder and the
  concrete builder) surfaces it from the facade with optional GPU acceleration.
- Bump AiDotNet.Tensors 0.114.0 -> 0.118.0 (brings Tensors #824, the native
  ANN kernel stack — the gating dependency).
- Remove the AiDotNet.Storage.Faiss project, its tests, the FaissNet package
  reference, and all solution/csproj wiring: the native path supersedes it and
  takes no external native dependency.

Tests: AnnVectorIndexTests 9/9 green on net471 + net10 (exact flat NN,
in-cluster recall for IVF/PQ/IVFPQ on separable clusters, Add/Remove/Clear/
AddBatch/cosine-normalization).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: franklinic

AiDotNet.sln

@@ -41,8 +41,6 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AiDotNet.Storage.Sqlite", "
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AiDotNet.Storage.Neo4j", "src\AiDotNet.Storage.Neo4j\AiDotNet.Storage.Neo4j.csproj", "{AC1D46B1-1711-4DC4-AD97-DBC6FA2BF396}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AiDotNet.Storage.Faiss", "src\AiDotNet.Storage.Faiss\AiDotNet.Storage.Faiss.csproj", "{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}"
-EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -185,18 +183,6 @@ Global
 		{BBC4C51F-3BFD-419C-9B59-ADD7AB006095}.Release|x64.Build.0 = Release|Any CPU
 		{BBC4C51F-3BFD-419C-9B59-ADD7AB006095}.Release|x86.ActiveCfg = Release|Any CPU
 		{BBC4C51F-3BFD-419C-9B59-ADD7AB006095}.Release|x86.Build.0 = Release|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Debug|x64.ActiveCfg = Debug|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Debug|x64.Build.0 = Debug|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Debug|x86.ActiveCfg = Debug|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Debug|x86.Build.0 = Debug|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Release|Any CPU.Build.0 = Release|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Release|x64.ActiveCfg = Release|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Release|x64.Build.0 = Release|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Release|x86.ActiveCfg = Release|Any CPU
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53}.Release|x86.Build.0 = Release|Any CPU
 		{B1427BFB-8A17-4735-8EC5-E594A612AB81}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{B1427BFB-8A17-4735-8EC5-E594A612AB81}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{B1427BFB-8A17-4735-8EC5-E594A612AB81}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -255,7 +241,6 @@ Global
 		{035B7687-2236-4D7F-97C5-8BA20567DD37} = {827E0CD3-B72D-47B6-A68D-7590B98EB39B}
 		{C1E3CF04-768E-46AE-A6EB-C9F9334365E6} = {66320409-64EC-F7C5-3DEF-65E7510DAAD1}
 		{BBC4C51F-3BFD-419C-9B59-ADD7AB006095} = {827E0CD3-B72D-47B6-A68D-7590B98EB39B}
-		{A1F5C7D2-9E3B-4C6A-8D2F-1B7E4A9C0D53} = {827E0CD3-B72D-47B6-A68D-7590B98EB39B}
 		{B1427BFB-8A17-4735-8EC5-E594A612AB81} = {66320409-64EC-F7C5-3DEF-65E7510DAAD1}
 		{D71746F5-5342-474C-B23E-4A07B29FA4F7} = {827E0CD3-B72D-47B6-A68D-7590B98EB39B}
 		{251CF282-40BA-452B-A563-FAE6B9826B8B} = {827E0CD3-B72D-47B6-A68D-7590B98EB39B}

Directory.Packages.props

@@ -248,8 +248,13 @@
          PersistentInputRegistry}; the src/Training mirror classes stay as the consumer-side primitives
          (the fused-primitive centralization in #1847/#1848 wires every consumer through them) and now
          run against the fixed engine. 0.113.0 is PUBLISHED to NuGet and is a superset of 0.112.0 (also
-         carries #765 compiled-ReduceMax axis fill), so all rationale above is retained. -->
-    <PackageVersion Include="AiDotNet.Tensors" Version="0.114.0" />
+         carries #765 compiled-ReduceMax axis fill), so all rationale above is retained.
+
+         Bumped 0.114.0 -> 0.118.0: brings AiDotNet.Tensors #824 — the native fused ANN kernel stack
+         (IAnnBackend + AnnPrimitives + AnnIndex: Flat/IVF/PQ/IVFPQ across all 7 backends). This is the
+         GATING dependency for the dependency-free NativeAnn vector index (AnnVectorIndex<T>) that
+         replaces the broken external FaissNet IVF/PQ path. Requires publishing Tensors 0.118.0. -->
+    <PackageVersion Include="AiDotNet.Tensors" Version="0.118.0" />
     <PackageVersion Include="AiDotNet.Native.OneDNN" Version="0.114.0" />
     <PackageVersion Include="AiDotNet.Native.OpenBLAS" Version="0.114.0" />
     <PackageVersion Include="AiDotNet.Native.CLBlast" Version="0.114.0" />
@@ -310,7 +315,6 @@
     <PackageVersion Include="Neo4j.Driver" Version="5.28.4" />
     <!-- Managed FAISS wrapper (native ANN: Flat/IVF/HNSW/PQ). Consumed only by the opt-in
          AiDotNet.Storage.Faiss metapackage; ships a net6.0 lib + win-x64 native runtime. -->
-    <PackageVersion Include="FaissNet" Version="1.1.0" />
     <PackageVersion Include="Pinecone.Client" Version="4.0.2" />
     <PackageVersion Include="StackExchange.Redis" Version="2.13.17" />
     <PackageVersion Include="Stripe.net" Version="52.1.0" />