docs(P6.4): repoint all doc links from the GitHub wiki to docs.wickra.org (#86)

The documentation now lives in the wickra-lib/wickra-docs VitePress repo and
will deploy to docs.wickra.org. Rewrite every tracked, user-facing wiki link
in the main repo to the new canonical site:

- docs/README.md, CONTRIBUTING.md, PULL_REQUEST_TEMPLATE.md
- bindings/{node,python,wasm}/README.md, examples/wasm/README.md
- repo-metadata.toml: wiki_url/wiki_git -> docs_url/docs_git

Page paths map 1:1 to VitePress clean URLs (e.g. /wiki/Quickstart-Rust.md ->
docs.wickra.org/Quickstart-Rust). The sync-about.yml wiki-sync step is left
untouched on purpose: it stays until the docs site is live (tracked as P8.3).
The GitHub wiki itself is not deleted yet for the same reason.

examples/wasm/README.md

@@ -58,7 +58,7 @@ indicators tracks those.
 
 ## See also
 
-- [Quickstart: WASM](https://github.com/wickra-lib/wickra/wiki/Quickstart-WASM.md) — module-load
+- [Quickstart: WASM](https://docs.wickra.org/Quickstart-WASM) — module-load
   flow, `wasm-pack` targets, and the streaming API.
 - [examples/README.md](../README.md) — cross-language index, including
   the Rust, Python and Node siblings of every demo above.