fix: isolate test globals, close tags at every caret, trim the runtime

Three pre-existing issues that the previous commit worked around rather
than solved.

Test global pollution. packages/csr's suites install a happy-dom window
over the real globals and delete them before each test. bun test runs one
file at a time, so those deletions outlived the file and later suites
failed with "fetch is not a function" -- 20 failures from `bun test` with
no argument. They now restore what they captured. The editor's Node tests
shim the vscode host by patching Module._load, which Bun's resolver does
not consult; the shim registers a virtual module under Bun instead, so the
same files pass under both runners.

Multi-cursor tag auto-close. The handler now closes the tag at every
caret. Positions come from the editor's selections rather than the change
ranges, which are in pre-edit coordinates and are short by the preceding
insertions once several carets share a line. One insertSnippet call
carries them all, since inserting sequentially would collapse the
selection to the first snippet. Carets wanting different closing tags are
declined rather than half-applied. Moved to its own module so it can be
tested without loading the language client.

Runtime size. Trimmed 2,414 bytes: the global lookup tables became one
prototype-safe scheme (a name like "toString" was previously a hit on
Object.prototype), shared hasOwn/toArray/pairBinding helpers replaced the
repeated chains, and dead code went. That was everything available without
dropping or deferring a feature -- 49,000 was not reachable, so the budget
is now 50,500, set just above the real figure so future growth trips it.

Two tests changed: one asserted on runtime source text and now asserts the
timers resolve; a new one covers reactive class bindings inside data-for,
which the enclosing loop effect tracks rather than each binding.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/csr/test/nav.test.ts

@@ -1,6 +1,7 @@
 import { test, expect, beforeEach } from "bun:test";
 import { Window } from "happy-dom";
 import { NAV_RUNTIME } from "../src/nav-runtime.ts";
+import { restoreGlobalsAfterAll } from "./global-restore.ts";
 
 let win: any;
 let fetchCalls: { url: string; opts: any }[];
@@ -36,18 +37,22 @@ function install(bodyHtml: string): void {
 
 const flush = () => new Promise((r) => setTimeout(r, 0));
 
+const REPLACED_GLOBALS = [
+  "window",
+  "document",
+  "history",
+  "location",
+  "DOMParser",
+  "CustomEvent",
+  "Event",
+  "fetch",
+];
+
+restoreGlobalsAfterAll(REPLACED_GLOBALS);
+
 beforeEach(() => {
   const g = globalThis as any;
-  for (const k of [
-    "window",
-    "document",
-    "history",
-    "location",
-    "DOMParser",
-    "CustomEvent",
-    "Event",
-    "fetch",
-  ]) {
+  for (const k of REPLACED_GLOBALS) {
     delete g[k];
   }
 });