chore: Set up GitHub Issue Templates

- Add `bug-report.yml` for structured bug reporting.
- Include a pre-submission checklist for bug reports, checking issue list and Shopify Liquid compatibility.
- Add `feature-request.yml` for structured feature requests.
- Include a pre-submission checklist for feature requests, checking the issue list.
- Configure `config.yml` to disable blank issues and link to GitHub Discussions for questions.
- Remove the deprecated `ISSUE_TEMPLATE.md`.

Author: osteele

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,68 @@
+name: Bug Report
+description: Report a bug in the Liquid template engine
+title: "[BUG] "
+labels: ["bug"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for taking the time to report a bug! Please fill out the form below to help us understand and fix the issue.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Pre-submission Checklist
+      description: Please verify you've completed these steps before submitting
+      options:
+        - label: I have searched the [issue list](https://github.com/osteele/liquid/issues) for similar issues
+          required: true
+        - label: I have tested my example against Shopify Liquid (not required if the issue is a panic or an error where `IsTemplateError` returns false)
+          required: false
+
+  - type: textarea
+    id: expected-behavior
+    attributes:
+      label: Expected Behavior
+      description: What did you expect to happen?
+      placeholder: Describe the expected behavior
+    validations:
+      required: true
+
+  - type: textarea
+    id: actual-behavior
+    attributes:
+      label: Actual Behavior
+      description: What actually happened?
+      placeholder: Describe what actually happened, including any error messages
+    validations:
+      required: true
+
+  - type: textarea
+    id: detailed-description
+    attributes:
+      label: Detailed Description
+      description: Provide a detailed description with example code, input data, and steps to reproduce
+      placeholder: |
+        Example:
+        ```go
+        template := `{{ "hello" | upcase }}`
+        engine := liquid.NewEngine()
+        out, err := engine.ParseAndRenderString(template, nil)
+        ```
+      render: markdown
+    validations:
+      required: true
+
+  - type: textarea
+    id: possible-solution
+    attributes:
+      label: Possible Solution
+      description: (Optional) Suggest a fix or reason for the bug
+      placeholder: If you have ideas about what might be causing this or how to fix it, please share
+
+  - type: input
+    id: version
+    attributes:
+      label: Version
+      description: What version of liquid are you using?
+      placeholder: e.g., v1.2.3 or commit SHA

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Question or Discussion
+    url: https://github.com/osteele/liquid/discussions
+    about: For questions or general discussion, please use GitHub Discussions

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,62 @@
+name: Feature Request
+description: Suggest a new feature or enhancement
+title: "[FEATURE] "
+labels: ["enhancement"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for your interest in improving the Liquid template engine! Please describe your feature request below.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Pre-submission Checklist
+      description: Please verify you've completed this step before submitting
+      options:
+        - label: I have searched the [issue list](https://github.com/osteele/liquid/issues) for similar feature requests
+          required: true
+
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem Description
+      description: What problem does this feature solve? Is your feature request related to a problem?
+      placeholder: I'm frustrated when... / It would be useful to have...
+    validations:
+      required: true
+
+  - type: textarea
+    id: proposed-solution
+    attributes:
+      label: Proposed Solution
+      description: Describe the solution you'd like
+      placeholder: |
+        What should the feature do? How should it work?
+
+        Example:
+        ```liquid
+        {{ variable | new_filter }}
+        ```
+    validations:
+      required: true
+
+  - type: textarea
+    id: alternatives
+    attributes:
+      label: Alternatives Considered
+      description: Describe any alternative solutions or features you've considered
+      placeholder: Have you considered workarounds or other approaches?
+
+  - type: textarea
+    id: shopify-compatibility
+    attributes:
+      label: Shopify Liquid Compatibility
+      description: Does this feature exist in Shopify Liquid? If so, please provide documentation or examples
+      placeholder: Link to Shopify Liquid docs or describe how it works in Shopify
+
+  - type: textarea
+    id: additional-context
+    attributes:
+      label: Additional Context
+      description: Add any other context, examples, or screenshots about the feature request