refactor: consolidate binary artifact interpretation and fixture ownership

Share exact ELF program-header facts across nine consumers while preserving their admission and precision policies. Centralize conformance path and digest binding, retain verifier-specific checks, and route fixture-owner changes to CI qualification.

src/domain/elfProgramHeader.ts

@@ -0,0 +1,30 @@
+import { err, ok } from "./result.js";
+
+/** Fixed ELF32/ELF64 program declarations; consumers own type, precision and mapping admission. */
+export const readElfProgramHeader = (
+  bytes: Uint8Array,
+  bits: 32 | 64,
+  littleEndian: boolean,
+) => {
+  const wide = bits === 64;
+  if (bytes.byteLength < (wide ? 56 : 32))
+    return err({
+      kind: "malformed" as const,
+      message: "ELF program header is truncated",
+    });
+  const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
+  const word = (at: number): bigint =>
+    wide
+      ? view.getBigUint64(at, littleEndian)
+      : BigInt(view.getUint32(at, littleEndian));
+  return ok({
+    type: view.getUint32(0, littleEndian),
+    flags: view.getUint32(wide ? 4 : 24, littleEndian),
+    offset: word(wide ? 8 : 4),
+    virtualAddress: word(wide ? 16 : 8),
+    physicalAddress: word(wide ? 24 : 12),
+    fileSize: word(wide ? 32 : 16),
+    memorySize: word(wide ? 40 : 20),
+    alignment: word(wide ? 48 : 28),
+  });
+};