Add issue template for submitting new instances

This commit introduces an issue template for users to submit
information about a PixivFE instance they want to add.

.forgejo/issue_template/add-instance.yaml

@@ -0,0 +1,101 @@
+name: 🌐 Add Instance
+description: Submit a new PixivFE instance to be added
+title: "Add instance: <domain-name>"
+labels: instance/add
+body:
+- type: markdown
+  attributes:
+    value: |
+      Provide the following details about the PixivFE instance you would like to add. In the issue title, replace `<domain-name>` with the instance's actual domain name.
+
+- type: input
+  id: domain-name
+  attributes:
+    label: Domain name
+    description: |
+      Provide the instance's [fully qualified domain name (FQDN)](https://en.wikipedia.org/wiki/Fully_qualified_domain_name) without a period at the end.
+
+      Example: `pixivfe.example.com`
+  validations:
+    required: true
+
+- type: input
+  id: url
+  attributes:
+    label: URL
+    description: |
+      Provide the complete URL for accessing the instance, including the protocol (e.g. `https://` for HTTPS).
+
+      Example: `https://pixivfe.example.com/`.
+  validations:
+    required: true
+
+- type: input
+  id: country
+  attributes:
+    label: Country
+    description: |
+      Provide the [ISO 3166-1 alpha-2 code](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2#Officially_assigned_code_elements) for the country where the instance is hosted.
+        
+      Example: Enter `US` for an instance hosted in the United States.
+  validations:
+    required: true
+
+- type: dropdown
+  id: cloudflare
+  attributes:
+    label: Cloudflare proxy
+    description: |
+      Answer "Yes" if the instance uses Cloudflare as a proxy. If Cloudflare is only used for DNS resolution (shown as a gray cloud icon in the Cloudflare DNS dashboard), answer "No".
+    options:
+      - "Yes"
+      - "No"
+  validations:
+    required: true
+
+- type: dropdown
+  id: analytics
+  attributes:
+    label: Analytics
+    description: |
+      Answer "Yes" or "No" to indicate if the instance uses any analytics.
+    options:
+      - "Yes"
+      - "No"
+  validations:
+    required: true
+
+- type: textarea
+  id: analytics-description
+  attributes:
+    label: Analytics description
+    description: |
+      If you answered "Yes" for analytics, describe what analytics platform or tools are used.
+  validations:
+    required: false
+
+- type: checkboxes
+  id: alternative-access
+  attributes:
+    label: Alternative access methods
+    description: Select any alternative access methods available for this instance.
+    options:
+      - label: Tor onion service
+      - label: I2P eepsite
+      - label: Lokinet
+      - label: Other (please specify in the details below)
+  validations:
+    required: false
+
+- type: textarea
+  id: alternative-access-details
+  attributes:
+    label: Alternative access details
+    description: |
+      If you selected any alternative access methods above, please provide the following details:
+      - For Tor: The .onion address (e.g. `pixivfe.onion`)
+      - For I2P: The I2P address (e.g. `pixivfe.i2p`)
+      - For Lokinet: The .loki address (e.g. `pixivfe.loki`)
+      - For other methods: The method name and corresponding address
+  validations:
+    required: false