feat: add build system, stubs, and npm packaging — openclaude is now runnable

- package.json with all 70+ dependencies
- Bun build script with feature flag shims, native module stubs, otel externals
- Stubs for ~15 missing source files (snapshot gaps)
- tsconfig.json for TypeScript
- bin/openclaude entry point
- Builds to single 19MB dist/cli.mjs
- Verified: --version and --help work

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/services/compact/cachedMicrocompact.ts

@@ -0,0 +1,12 @@
+// Stub — cachedMicrocompact not included in source snapshot (feature-gated)
+export function isCachedMicrocompactEnabled(): boolean {
+  return false
+}
+
+export function isModelSupportedForCacheEditing(_model: string): boolean {
+  return false
+}
+
+export function getCachedMCConfig() {
+  return null
+}

src/services/compact/snipCompact.ts

@@ -0,0 +1,4 @@
+// Stub — snipCompact not included in source snapshot
+export function snipCompact() {
+  return null
+}