feat: Implemented crypto module and added github workflows

.github/ISSUE_TEMPLATE/bug_report.md

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+---
+name: Bug Report
+about: Create a report to help us improve
+title: '[BUG] '
+labels: bug
+assignees: ''
+---
+
+## Bug Description
+
+A clear and concise description of what the bug is.
+
+## To Reproduce
+
+Steps to reproduce the behavior:
+1. ...
+2. ...
+3. ...
+
+## Expected Behavior
+
+A clear and concise description of what you expected to happen.
+
+## Actual Behavior
+
+What actually happened.
+
+## Code Sample
+
+```zig
+// Your code here
+```
+
+## Environment
+
+- **OS**: [e.g., Ubuntu 22.04, macOS 13, Windows 11]
+- **Zig Version**: [e.g., 0.14.1]
+- **Zigeth Version**: [e.g., v0.1.0]
+
+## Additional Context
+
+Add any other context about the problem here.
+
+## Stack Trace
+
+```
+// Paste any relevant stack traces or error messages here
+```
+

.github/ISSUE_TEMPLATE/feature_request.md

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+---
+name: Feature Request
+about: Suggest an idea for this project
+title: '[FEATURE] '
+labels: enhancement
+assignees: ''
+---
+
+## Feature Description
+
+A clear and concise description of the feature you'd like to see.
+
+## Problem Statement
+
+Is your feature request related to a problem? Please describe.
+Ex. I'm always frustrated when [...]
+
+## Proposed Solution
+
+Describe the solution you'd like to see implemented.
+
+## Alternative Solutions
+
+Describe any alternative solutions or features you've considered.
+
+## Use Case
+
+Describe the use case for this feature. How would you use it?
+
+```zig
+// Example code showing how the feature would be used
+```
+
+## Benefits
+
+What are the benefits of implementing this feature?
+- ...
+- ...
+
+## Potential Drawbacks
+
+Are there any potential drawbacks or considerations?
+- ...
+- ...
+
+## Additional Context
+
+Add any other context, mockups, or examples about the feature request here.
+

.github/PULL_REQUEST_TEMPLATE.md

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+## Description
+
+<!-- Provide a brief description of the changes in this PR -->
+
+## Type of Change
+
+<!-- Mark the relevant option with an "x" -->
+
+- [ ] Bug fix (non-breaking change which fixes an issue)
+- [ ] New feature (non-breaking change which adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+- [ ] Documentation update
+- [ ] Performance improvement
+- [ ] Code refactoring
+- [ ] Test improvement
+
+## Testing
+
+<!-- Describe the tests you ran to verify your changes -->
+
+- [ ] All existing tests pass (`zig build test`)
+- [ ] Added new tests for the changes
+- [ ] Manual testing performed
+
+## Checklist
+
+- [ ] My code follows the Zig style guide (`zig build fmt`)
+- [ ] Linting passes (`zig build lint`)
+- [ ] I have commented my code, particularly in hard-to-understand areas
+- [ ] I have updated the documentation accordingly
+- [ ] My changes generate no new warnings
+- [ ] I have added tests that prove my fix is effective or that my feature works
+- [ ] New and existing unit tests pass locally with my changes
+
+## Related Issues
+
+<!-- Link any related issues here using #issue_number -->
+
+Closes #
+
+## Additional Notes
+
+<!-- Add any additional notes or context about the PR here -->
+

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+    branches: [ main, master ]
+  pull_request:
+    branches: [ main, master ]
+
+jobs:
+  lint:
+    name: Lint and Format Check
+    runs-on: ubuntu-latest
+    env:
+      ZIG_GLOBAL_CACHE_DIR: ${{ github.workspace }}/.zig-cache/global
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Zig
+        uses: goto-bus-stop/setup-zig@v2
+        with:
+          version: 0.14.1
+
+      - name: Check formatting
+        run: zig build fmt-check
+
+      - name: Run linting
+        run: zig build lint
+
+  test:
+    name: Test on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+
+    env:
+      ZIG_GLOBAL_CACHE_DIR: ${{ github.workspace }}/.zig-cache/global
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Zig
+        uses: goto-bus-stop/setup-zig@v2
+        with:
+          version: 0.14.1
+
+      - name: Cache Zig artifacts
+        uses: actions/cache@v4
+        with:
+          path: |
+            .zig-cache
+            zig-out
+          key: ${{ runner.os }}-zig-test-${{ hashFiles('build.zig', 'build.zig.zon', 'src/**/*.zig') }}
+          restore-keys: |
+            ${{ runner.os }}-zig-test-
+            ${{ runner.os }}-zig-
+
+      - name: Build library
+        run: zig build
+
+      - name: Run tests
+        run: zig build test
+
+  build:
+    name: Build on ${{ matrix.os }} (${{ matrix.optimize }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        optimize: [Debug, ReleaseSafe, ReleaseFast, ReleaseSmall]
+
+    env:
+      ZIG_GLOBAL_CACHE_DIR: ${{ github.workspace }}/.zig-cache/global
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Zig
+        uses: goto-bus-stop/setup-zig@v2
+        with:
+          version: 0.14.1
+
+      - name: Cache Zig artifacts
+        uses: actions/cache@v4
+        with:
+          path: |
+            .zig-cache
+            zig-out
+          key: ${{ runner.os }}-zig-${{ matrix.optimize }}-${{ hashFiles('build.zig', 'build.zig.zon', 'src/**/*.zig') }}
+          restore-keys: |
+            ${{ runner.os }}-zig-${{ matrix.optimize }}-
+            ${{ runner.os }}-zig-
+
+      - name: Build (${{ matrix.optimize }})
+        run: zig build -Doptimize=${{ matrix.optimize }}
+
+  coverage:
+    name: Code Coverage
+    runs-on: ubuntu-latest
+    env:
+      ZIG_GLOBAL_CACHE_DIR: ${{ github.workspace }}/.zig-cache/global
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Zig
+        uses: goto-bus-stop/setup-zig@v2
+        with:
+          version: 0.14.1
+
+      - name: Run tests with coverage
+        run: zig build test
+
+      - name: Generate coverage report
+        run: |
+          echo "Coverage reporting not yet configured"
+          # TODO: Add coverage reporting when available
+
+  docs:
+    name: Build Documentation
+    runs-on: ubuntu-latest
+    env:
+      ZIG_GLOBAL_CACHE_DIR: ${{ github.workspace }}/.zig-cache/global
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Zig
+        uses: goto-bus-stop/setup-zig@v2
+        with:
+          version: 0.14.1
+
+      - name: Build documentation
+        run: zig build docs
+
+      - name: Upload documentation
+        uses: actions/upload-artifact@v4
+        with:
+          name: docs
+          path: zig-out/docs/
+
+  summary:
+    name: CI Summary
+    runs-on: ubuntu-latest
+    needs: [lint, test, build]
+    if: always()
+    steps:
+      - name: Check results
+        run: |
+          if [ "${{ needs.lint.result }}" == "failure" ] || \
+             [ "${{ needs.test.result }}" == "failure" ] || \
+             [ "${{ needs.build.result }}" == "failure" ]; then
+            echo "❌ CI failed"
+            exit 1
+          else
+            echo "✅ All CI checks passed"
+          fi
+