Add GitHub issue templates and update CLAUDE.md

Issue templates (.github/ISSUE_TEMPLATE/):
  - feature.yml: Overview, Problem, Proposal (checklist), Evidence,
    Scope/Non-goals, Benchmark/Performance, Breaking changes, Related issues
  - bug.yml: Overview, Reproduction (C# syntax), Expected, Actual,
    Workaround, Root cause, Related issues
  - config.yml: blank issues allowed

CLAUDE.md updates:
  - GitHub Issues section: added Feature/Enhancement and Bug Report
    format specifications matching the issue templates
  - Test Categories section: documents [TestCategory("OpenBugs")] and
    [TestCategory("WindowsOnly")] convention and CI filter mapping
  - CI Pipeline section: pointer to build-and-release.yml

Author: Nucs

.claude/CLAUDE.md

@@ -307,7 +307,29 @@ switch (nd.typecode)
 ```
 
 ## GitHub Issues
-Create issues on `SciSharp/NumSharp` via `gh issue create` when the user requests it. `GH_TOKEN` is available in the environment.
+
+Create issues on `SciSharp/NumSharp` via `gh issue create`. `GH_TOKEN` is available via the `env-tokens` skill.
+
+### Feature / Enhancement
+
+- **Overview**: 1-2 sentence summary of what and why
+- **Problem**: What's broken or missing, why it matters
+- **Proposal**: What to change, with a task checklist (`- [ ]`)
+- **Evidence**: Data, benchmarks, or references supporting the proposal
+- **Scope / Non-goals**: What this issue does NOT cover (prevent scope creep)
+- **Benchmark / Performance** (if applicable): Before/after numbers, methodology, what to measure
+- **Breaking changes** table (if any): Change | Impact | Migration
+- **Related issues**: Link dependencies
+
+### Bug Report
+
+- **Overview**: 1-2 sentence summary of the bug and its impact
+- **Reproduction**: Minimal code to trigger the bug
+- **Expected**: Correct behavior (include NumPy output as source of truth)
+- **Actual**: What NumSharp does instead (error message, wrong output, crash)
+- **Workaround** (if any): How users can avoid the bug today
+- **Root cause** (if known): File, line, why it happens
+- **Related issues**: Link duplicates or upstream causes
 
 ## Build & Test
 
@@ -316,6 +338,23 @@ dotnet build -v q --nologo "-clp:NoSummary;ErrorsOnly" -p:WarningLevel=0
 dotnet test -v q --nologo "-clp:ErrorsOnly" test/NumSharp.UnitTest/NumSharp.UnitTest.csproj
 ```
 
+## Test Categories
+
+Tests are filtered by `[TestCategory]` attributes. Adding new bug reproductions or platform-specific tests only requires the right attribute — no CI workflow changes.
+
+| Category | Purpose | CI filter |
+|----------|---------|-----------|
+| `OpenBugs` | Known-failing bug reproductions. Remove category when fixed. | `TestCategory!=OpenBugs` (all platforms) |
+| `WindowsOnly` | Requires GDI+/System.Drawing.Common | `TestCategory!=WindowsOnly` (Linux/macOS) |
+
+Apply at class level (`[TestClass][TestCategory("OpenBugs")]`) or individual method level (`[TestMethod][TestCategory("OpenBugs")]`).
+
+**OpenBugs files**: `OpenBugs.cs` (broadcast bugs), `OpenBugs.Bitmap.cs` (bitmap bugs). When a bug is fixed, the test starts passing — remove the `OpenBugs` category and move to a permanent test class.
+
+## CI Pipeline
+
+`.github/workflows/build-and-release.yml` — test on 3 OSes (Windows/Ubuntu/macOS), build NuGet on tag push, create GitHub Release, publish to nuget.org.
+
 ## Scripting with `dotnet run` (.NET 10 file-based apps)
 
 ### Accessing Internal Members

.github/ISSUE_TEMPLATE/bug.yml

@@ -0,0 +1,54 @@
+name: Bug Report
+description: Report a bug or incorrect behavior
+labels: ["bug"]
+body:
+  - type: textarea
+    id: overview
+    attributes:
+      label: Overview
+      description: 1-2 sentence summary of the bug and its impact.
+    validations:
+      required: true
+
+  - type: textarea
+    id: reproduction
+    attributes:
+      label: Reproduction
+      description: Minimal code to trigger the bug.
+      render: csharp
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected
+      description: Correct behavior. Include NumPy output as source of truth where applicable.
+    validations:
+      required: true
+
+  - type: textarea
+    id: actual
+    attributes:
+      label: Actual
+      description: What NumSharp does instead (error message, wrong output, crash).
+    validations:
+      required: true
+
+  - type: textarea
+    id: workaround
+    attributes:
+      label: Workaround
+      description: How users can avoid the bug today (if any).
+
+  - type: textarea
+    id: root-cause
+    attributes:
+      label: Root cause
+      description: File, line, why it happens (if known).
+
+  - type: textarea
+    id: related
+    attributes:
+      label: Related issues
+      description: Link duplicates or upstream causes.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1 @@
+blank_issues_enabled: true

.github/ISSUE_TEMPLATE/feature.yml

@@ -0,0 +1,60 @@
+name: Feature / Enhancement
+description: Propose a new feature or improvement
+labels: ["enhancement"]
+body:
+  - type: textarea
+    id: overview
+    attributes:
+      label: Overview
+      description: 1-2 sentence summary of what and why.
+    validations:
+      required: true
+
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem
+      description: What's broken or missing, and why it matters.
+    validations:
+      required: true
+
+  - type: textarea
+    id: proposal
+    attributes:
+      label: Proposal
+      description: What to change. Use a task checklist (`- [ ]`) for individual steps.
+      placeholder: |
+        - [ ] Step 1
+        - [ ] Step 2
+    validations:
+      required: true
+
+  - type: textarea
+    id: evidence
+    attributes:
+      label: Evidence
+      description: Data, benchmarks, references, or NumPy behavior supporting the proposal.
+
+  - type: textarea
+    id: scope
+    attributes:
+      label: Scope / Non-goals
+      description: What this issue does NOT cover (prevent scope creep).
+
+  - type: textarea
+    id: benchmark
+    attributes:
+      label: Benchmark / Performance
+      description: Before/after numbers, methodology, what to measure (if applicable).
+
+  - type: textarea
+    id: breaking-changes
+    attributes:
+      label: Breaking changes
+      description: Use a table if needed (Change | Impact | Migration).
+
+  - type: textarea
+    id: related
+    attributes:
+      label: Related issues
+      description: Link dependencies or related issues.