feat(php): PHP code intelligence via Intelephense - on-demand install, full LSP parity

[abose]

PHP now gets the same intelligence as JS/TS: completion with a signature
docs popup, hover with full PHP-manual docs, signature help, diagnostics,
jump-to-definition, find references and quickfix plumbing - all on the
shared LSP framework via a new desktop-only PHPSupport default extension.

Licensing shapes the design: the Intelephense server is proprietary
freeware whose license forbids bundling, but permits individual users to
pair it with an LSP-capable editor. So it is NOT shipped - on the first
PHP file the user is offered it (SUBTLE prompt toast with Install/Not Now
and a "Powered by Intelephense" link, once per project per session, plus
a persistent Problems-panel Install row mirroring the TS enable flow).
Consent triggers a pinned npm install intelephense@1.18.5 into
/lspServers/intelephense/ through the existing bundled-npm node
plumbing, tracked as a status-bar TaskManager task with phase progress;
success auto-starts the server. Version upgrades (pin bumps) reinstall
silently and pass clearCache once. Preferences: php.codeIntelligence
(master switch) and php.licenseKey (premium licenceKey; the standard
global licence file also works untouched - the server reads it itself).
Cross-platform by construction: no .bin shims, no shell, array-args npm,
central VFS->platform path conversion.

Framework changes:

• src-node/lsp-client.js: an absolute command path ending .js is spawned
  on our own node runtime (process.execPath) - user-local servers run
  identically on Windows/macOS/Linux.
• LSPClient client capabilities now declare completionItem.resolveSupport
  (documentation, detail) - LSP 3.16 servers may gate lazy resolution on
  it. Verified empirically that intelephense provides NO completion-item
  documentation either way (its rich docs come via hover); hence:
• DefaultProviders composes the docs-popup signature from
  label + labelDetails.detail + return type when a server splits the
  signature across fields (intelephense) - previously the popup showed a
  bare return type. vtsls (whole signature in detail) is untouched.
  Long detail strings (>32 chars) no longer render inline in hint rows;
  the docs popup carries them.

Ecosystem fixes for mixed php/html documents:

• JavaScriptCodeHints: inline-script host languages (html, php) keep
  their Tern session even when an LSP claims the document language -
  intelephense serves only PHP, so without this every embedded <script>
  in .php files would lose JS intelligence.
• html-lint: php regions are blanked (same-length whitespace, newlines
  kept, so positions stay valid) before html-validate runs - kills the
  "failed to tokenize <?php" parser-error noise on every php file while
  still linting the surrounding HTML; pure-php files lint clean.
• gulpfile: PHPSupport registered as a minifyable extension; dist cache
  asset limit raised 75MB -> 78MB (recent features pushed CI past it).

Tests: new integration:PHP LSP 5/5 against a really-installed server
(install via ServerInstaller.installNow, parse diagnostics warm-up,
provider-active flags, hover docs, jump-to-definition, and the
embedded-JS Tern regression). Regressions: integration:TypeScript LSP
20/20 (including after the capability change), integration:JSON LSP 3/3,
releaseProd green (72.96 MB dist).

[sonarqubecloud]

Quality Gate failed

Failed conditions
4.9% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud