Add GitHub Issues section to CLAUDE.md

Adds a 'GitHub Issues' section to .claude/CLAUDE.md that documents using `gh issue create` for SciSharp/NumSharp and notes GH_TOKEN availability via the env-tokens skill. Provides structured templates for Feature/Enhancement and Bug Report issues (checklists and fields such as overview, problem/proposal, evidence, scope, benchmarks, breaking changes, reproduction, expected/actual behavior, workaround, root cause, and related issues) to standardize reporting.

Author: Nucs

.claude/CLAUDE.md

@@ -313,6 +313,31 @@ dotnet build -v q --nologo "-clp:NoSummary;ErrorsOnly" -p:WarningLevel=0
 dotnet test -v q --nologo "-clp:ErrorsOnly" test/NumSharp.UnitTest/NumSharp.UnitTest.csproj
 ```
 
+## GitHub Issues
+
+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
+
 ## Scripting with `dotnet run` (.NET 10 file-based apps)
 
 ### Accessing Internal Members