fix(bridge): gate getSourceFileByPath on program membership (issue #7)

Stock Program.getSourceFileByPath returns undefined for non-members;
Project.containsScriptInfo relies on that for 'does this project
contain the file'. The thin program's ungated byPath materialized an
SF for ANY path under tsserver, so containsFile over-reported and the
session's per-project references worker routed findReferences into
non-member projects — whose gated getSourceFile then threw 'Could not
find source file'. Surfaced whenever files from two tsconfig projects
were open and a references search crossed into the other project's
files (e.g. volar component-meta + tsc umbrella in one session).

Mirror the getSourceFile gate (lib files stay permissive). With both
layers fixed, the #7 repro scenario returns byte-identical reference
sets to stock (102/102, 103/103); sim-nav 37,409 units new=0; volar
suite 205/205.

Author: johnsoncodehk

patches/typescript/overlay/src/compiler/tsgoChecker.ts

@@ -5043,6 +5043,18 @@ export function createTsgoProgram(
         // toLineColumnOffset (go-to-definition span conversion) sees real line maps.
         getSourceFileByPath: (path: any) => {
             const pathStr = String(path);
+            // Membership gate (issue #7): stock Program.getSourceFileByPath
+            // returns undefined for non-members — Project.containsScriptInfo
+            // relies on that to answer "does this project contain the file".
+            // Ungated, tsserver materialized an SF for ANY path here, so
+            // containsFile over-reported and the session's per-project
+            // references worker routed findReferences into non-member
+            // projects whose (gated) getSourceFile then threw "Could not find
+            // source file". Lib files keep the permissive path, mirroring
+            // getSourceFile above.
+            if (!isHostLibFile(toHostFileName(pathStr)) && !programContainsFile(pathStr)) {
+                return undefined;
+            }
             // Pure-disk lint: the builder's affected-file drain calls this once
             // per changed file (and per graph node on incremental runs). The
             // fileHasHostSourceContent probe below would CREATE a host snapshot