feat: add Go, Rust, Java, PHP, TypeScript, and C/C++ docs shortcuts

The rest of the languages from #25, each probed for the cheapest shape
that works:

- go: pkg.go.dev renders search on the server, so 'search' is a plain
  URL and 'pkg <path>' opens a package page.
- php: manual-lookup.php sends an exact function name straight to its
  manual page, so 'fn array_map' lands on the function doc; fuzzy
  search goes through DuckDuckGo since the suggestions render behind
  the manual's own TOC.
- cpp: cppreference's new static site has clean /cpp/ and /c/ paths;
  its native search page is bare links oc refuses as unreadable, so
  'search' goes through DuckDuckGo.
- rust: std and doc page opens; rustdoc's search-index.js format is
  version-fragile, so 'search' goes through DuckDuckGo.
- java: Javadoc opens pinned to javase/26, the current GA (27
  redirects there); the typeSearchIndex file lacks the module names a
  URL needs, so 'search' goes through DuckDuckGo.
- ts: handbook page opens; the site searches via Algolia client-side,
  so DuckDuckGo again.
- learn gets a 'dotnet <api>' verb, since .NET API docs already live
  there.

README table and prose and the skill notes cover the new sites.

clis/php.net.json

@@ -0,0 +1,8 @@
+{
+  "domain": "php.net",
+  "commands": {
+    "fn": { "open": "https://www.php.net/manual-lookup.php?pattern={name}", "args": ["name"] },
+    "doc": { "open": "https://www.php.net/manual/en/{path}.php", "args": ["path"] },
+    "search": { "open": "https://html.duckduckgo.com/html/?q=site%3Aphp.net+{query}", "args": ["query"] }
+  }
+}