Add a field for AI policy compliance in the issues/PRs templates (#5803)

* Convert issue templates to Issue Forms with AI policy disclosure

Convert the 3 markdown issue templates (.md) to GitHub Issue Forms (.yml)
to enable interactive form elements, and add an AI disclosure section per
the AI Policy (AI_POLICY.md):

- Required checkbox to acknowledge having read the AI Policy
- Required dropdown for AI usage (none / fully / partially with explanation)
- Optional input for model(s) used (open-weight examples in placeholder)
- Optional input for tool(s) used (FOSS examples in placeholder)
- Optional textarea to explain how AI was used (for the partial option)

The existing template content and structure is preserved, only converted
from markdown to the Issue Forms schema.

* Align pull request template with AI policy disclosure

Update the pull request template to match the AI disclosure standards
introduced in the issue templates:

- Use relative link to AI_POLICY.md instead of absolute GitHub URL
- Update dropdown wording to match issue forms
- Use open-weight models in placeholder examples
- Use FOSS tools in placeholder examples
- Add 'How was AI used?' section for the partial-usage explanation

* Fix assignees field type in issue templates

Use an empty array instead of an empty string for the assignees field,
as required by the GitHub Issue Forms schema.

* Enhance the PR template

* Reword the issue templates to be consistent with the PR template

* Enhance the PR template

* Typo coming from the original template

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Better wording for what comes from the original templates

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Switch to full URLs since relative URL break inconsistently

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,81 @@
+name: Feature request
+description: Suggest an idea for this project
+title: "[Feature request] "
+labels: ["feature-request"]
+assignees: []
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Please use the search function to check if the desired function has already been requested by someone else
+        If you want to suggest an enhancement to an existing feature please use "Enhancement" instead
+        If you want to report a bug, please use "Bug report" instead
+  - type: textarea
+    id: problem
+    attributes:
+      label: Is your feature request related to a problem? Please describe.
+      description: A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+    validations:
+      required: true
+  - type: textarea
+    id: solution
+    attributes:
+      label: Describe the solution you'd like
+      description: A clear and concise description of what you want to happen.
+    validations:
+      required: true
+  - type: textarea
+    id: alternatives
+    attributes:
+      label: Describe alternatives you've considered
+      description: A clear and concise description of any alternative solutions or features you've considered.
+    validations:
+      required: false
+  - type: textarea
+    id: context
+    attributes:
+      label: Additional context
+      description: Add any other context or screenshots about the feature request here.
+    validations:
+      required: false
+  - type: checkboxes
+    id: ai-policy
+    attributes:
+      label: AI Policy
+      options:
+        - label: I have read the [AI Policy](https://github.com/iv-org/invidious/blob/master/AI_POLICY.md) and understand the disclosure requirements
+          required: true
+  - type: dropdown
+    id: ai-usage
+    attributes:
+      label: AI usage
+      description: Did you use AI to help create this issue?
+      options:
+        - AI was not used to write this issue
+        - AI was used to fully write this issue
+        - AI was used to partially create this issue (explain how)
+    validations:
+      required: true
+  - type: input
+    id: ai-models
+    attributes:
+      label: Model(s) used
+      description: If you used AI, list the EXACT model(s) used. Leave empty if you did not use AI.
+      placeholder: "e.g. Llama 3.1, Mistral, Qwen 2.5, DeepSeek-R1"
+    validations:
+      required: false
+  - type: input
+    id: ai-tools
+    attributes:
+      label: Tool(s) used
+      description: If you used AI, list the tool(s) used to interact with it. Leave empty if you did not use AI.
+      placeholder: "e.g. Ollama, Open WebUI, Continue"
+    validations:
+      required: false
+  - type: textarea
+    id: ai-explanation
+    attributes:
+      label: How was AI used?
+      description: If you selected "AI was used to partially create this issue (explain how)" above, explain how AI was used here. Leave empty otherwise.
+    validations:
+      required: false