ci: add issue and PR templates with bilingual support

Add GitHub issue templates (bug report, feature request, documentation
issue, question) and PR template. All templates use bilingual format
(English + Chinese) to support the international community.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,12 @@
+blank_issues_enabled: false
+contact_links:
+  - name: "Security Vulnerabilities / 安全漏洞"
+    url: "https://github.com/farion1231/cc-switch/security/advisories/new"
+    about: |
+      Report security vulnerabilities through GitHub Security Advisories.
+      请通过 GitHub 安全公告报告安全漏洞。
+  - name: "Discussions / 讨论区"
+    url: "https://github.com/farion1231/cc-switch/discussions"
+    about: |
+      General discussions and community help.
+      一般讨论和社区帮助。