feat: add platform-aware worker architecture with ARM64 support

Implement platform-specific Dockerfile selection and graceful tool degradation to support both x86_64 and ARM64 (Apple Silicon) platforms.

**Backend Changes:**
- Add system info API endpoint (/system/info) exposing host filesystem paths
- Add FUZZFORGE_HOST_ROOT environment variable to backend service
- Add graceful degradation in MobSF activity for ARM64 platforms

**CLI Changes:**
- Implement multi-strategy path resolution (backend API, .fuzzforge marker, env var)
- Add platform detection (linux/amd64 vs linux/arm64)
- Add worker metadata.yaml reading for platform capabilities
- Auto-select appropriate Dockerfile based on detected platform
- Pass platform-specific env vars to docker-compose

**Worker Changes:**
- Create workers/android/metadata.yaml defining platform capabilities
- Rename Dockerfile -> Dockerfile.amd64 (full toolchain with MobSF)
- Create Dockerfile.arm64 (excludes MobSF due to Rosetta 2 incompatibility)
- Update docker-compose.yml to use ${ANDROID_DOCKERFILE} variable

**Workflow Changes:**
- Handle MobSF "skipped" status gracefully in workflow
- Log clear warnings when tools are unavailable on platform

**Key Features:**
- Automatic platform detection and Dockerfile selection
- Graceful degradation when tools unavailable (MobSF on ARM64)
- Works from any directory (backend API provides paths)
- Manual override via environment variables
- Clear user feedback about platform and selected Dockerfile

**Benefits:**
- Android workflow now works on Apple Silicon Macs
- No code changes needed for other workflows
- Convention established for future platform-specific workers

Closes: MobSF Rosetta 2 incompatibility issue
Implements: Platform-aware worker architecture (Option B)

workers/android/metadata.yaml

@@ -0,0 +1,42 @@
+# Android Worker Metadata
+#
+# Platform-specific configuration for Android security analysis worker.
+# This file defines which Dockerfile to use for each platform and what tools
+# are available on that platform.
+
+name: android
+version: "1.0.0"
+description: "Android application security testing worker with Jadx, OpenGrep, and MobSF"
+
+# Default platform when auto-detection fails or metadata is not platform-aware
+default_platform: linux/amd64
+
+# Platform-specific configurations
+platforms:
+  # x86_64 / Intel / AMD platform (full toolchain including MobSF)
+  linux/amd64:
+    dockerfile: Dockerfile.amd64
+    description: "Full Android toolchain with MobSF support"
+    supported_tools:
+      - jadx          # APK decompiler
+      - opengrep      # Static analysis with custom Android rules
+      - mobsf         # Mobile Security Framework
+      - frida         # Dynamic instrumentation
+      - androguard    # Python APK analysis
+
+  # ARM64 / Apple Silicon platform (MobSF excluded due to Rosetta limitations)
+  linux/arm64:
+    dockerfile: Dockerfile.arm64
+    description: "Android toolchain without MobSF (ARM64/Apple Silicon compatible)"
+    supported_tools:
+      - jadx          # APK decompiler
+      - opengrep      # Static analysis with custom Android rules
+      - frida         # Dynamic instrumentation
+      - androguard    # Python APK analysis
+    disabled_tools:
+      mobsf: "Incompatible with Rosetta 2 emulation (requires syscall 284: copy_file_range)"
+    notes: |
+      MobSF cannot run under Rosetta 2 on Apple Silicon Macs due to missing
+      syscall implementations. The workflow will gracefully skip MobSF analysis
+      on this platform while still providing comprehensive security testing via
+      Jadx decompilation and OpenGrep static analysis.