feat(github): accept issues on GitHub and auto-forward to Gitea

GitHub mirror previously redirected issue reporters to Gitea, which
requires login. Now GitHub Issues are accepted directly via form
templates (bug report + feature request) and a workflow forwards
new issues to Gitea with label mapping and provenance header.

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,46 @@
+name: Bug Report
+description: Something isn't working as expected
+labels:
+  - bug
+body:
+  - type: checkboxes
+    id: search
+    attributes:
+      label: Before filing
+      options:
+        - label: I searched existing issues and didn't find a match
+          required: true
+  - type: textarea
+    id: description
+    attributes:
+      label: What happened?
+      description: Include what you expected to happen instead.
+      placeholder: |
+        When I run `uptop`, the TUI crashes after 10 seconds.
+        I expected it to keep running and display monitor status.
+    validations:
+      required: true
+  - type: textarea
+    id: reproduction
+    attributes:
+      label: Steps to reproduce
+      placeholder: |
+        1. Run `uptop`
+        2. Wait ~10 seconds
+        3. TUI crashes with panic
+    validations:
+      required: true
+  - type: textarea
+    id: environment
+    attributes:
+      label: Environment & logs
+      description: Output of `uptop version`, OS, terminal. Paste any errors below.
+      render: shell
+      placeholder: |
+        uptop 0.1.0 (abc1234, 2026-06-17)
+        OS: Debian 13
+        Terminal: Ghostty
+
+        [paste any error output here]
+    validations:
+      required: false

.github/ISSUE_TEMPLATE/config.yml

@@ -1,8 +1 @@
 blank_issues_enabled: false
-contact_links:
-  - name: Report a Bug
-    url: https://gitea.lerkolabs.com/lerkolabs/uptop/issues/new?template=bug_report.yaml
-    about: Report bugs on our Gitea instance
-  - name: Request a Feature
-    url: https://gitea.lerkolabs.com/lerkolabs/uptop/issues/new?template=feature_request.yaml
-    about: Suggest features on our Gitea instance

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,20 @@
+name: Feature Request
+description: Suggest a new feature or enhancement
+labels:
+  - feature
+body:
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem
+      description: What's frustrating or missing?
+      placeholder: I find myself always needing to ...
+    validations:
+      required: true
+  - type: textarea
+    id: solution
+    attributes:
+      label: Proposed solution
+      description: How would you like this to work?
+    validations:
+      required: false