chore(migration): switch org to wickra-lib and maintainer email to wickra.lib@gmail.com (#59)

Introduce repo-metadata.toml as single source of truth for repo identity
(org slug, maintainer email, canonical URLs) and add sync-metadata.yml
workflow with a Python audit script that fails CI if any tracked file
drifts back to pre-migration values.

Bulk-replace across 24 tracked files:
- kingchenc/wickra -> wickra-lib/wickra (URL segment)
- kingchencp@gmail.com -> wickra.lib@gmail.com (maintainer email)
- @kingchenc -> @wickra-lib (CODEOWNERS mention only)

Person-name credits are preserved: LICENSE copyright holder, Cargo.toml
authors handle, and CHANGELOG historical @kingchenc reference all remain
unchanged. Crate / PyPI / npm package names also untouched.

Merge this PR only after the kingchenc/wickra -> wickra-lib/wickra org
transfer has happened on the GitHub side, otherwise all badges and
repository links 404 until the transfer is performed.

.github/ISSUE_TEMPLATE/config.yml

@@ -1,8 +1,8 @@
 blank_issues_enabled: false
 contact_links:
   - name: Security vulnerability
-    url: https://github.com/kingchenc/wickra/security/advisories/new
+    url: https://github.com/wickra-lib/wickra/security/advisories/new
     about: Report security issues privately — do not open a public issue.
   - name: Question or discussion
-    url: https://github.com/kingchenc/wickra/discussions
+    url: https://github.com/wickra-lib/wickra/discussions
     about: Ask usage questions and discuss ideas here.