community: add issue/PR templates, code of conduct, update contributing guide

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,39 @@
+name: Bug Report
+description: Report a bug or unexpected behavior
+labels: ["bug"]
+body:
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: What happened? What did you expect?
+    validations:
+      required: true
+  - type: textarea
+    id: steps
+    attributes:
+      label: Steps to reproduce
+      description: How can we reproduce the issue?
+  - type: input
+    id: version
+    attributes:
+      label: NORA version
+      placeholder: "0.2.32"
+  - type: dropdown
+    id: protocol
+    attributes:
+      label: Registry protocol
+      options:
+        - Docker
+        - npm
+        - Maven
+        - PyPI
+        - Cargo
+        - Raw
+        - UI/Dashboard
+        - Other
+  - type: textarea
+    id: logs
+    attributes:
+      label: Logs / error output
+      render: shell

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,30 @@
+name: Feature Request
+description: Suggest a new feature or improvement
+labels: ["enhancement"]
+body:
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem
+      description: What problem does this solve?
+    validations:
+      required: true
+  - type: textarea
+    id: solution
+    attributes:
+      label: Proposed solution
+      description: How would you like it to work?
+  - type: dropdown
+    id: protocol
+    attributes:
+      label: Related protocol
+      options:
+        - Docker
+        - npm
+        - Maven
+        - PyPI
+        - Cargo
+        - Raw
+        - CLI
+        - UI/Dashboard
+        - General

.github/pull_request_template.md

@@ -0,0 +1,15 @@
+## What does this PR do?
+
+<!-- Brief description of the change -->
+
+## Related issue
+
+<!-- Link to issue, e.g. Fixes #123 -->
+
+## Checklist
+
+- [ ] `cargo fmt` passes
+- [ ] `cargo clippy` passes with no warnings
+- [ ] `cargo test --lib --bin nora` passes
+- [ ] New functionality includes tests
+- [ ] CHANGELOG.md updated (if user-facing change)