chore(scaffold): initial SilverMetal program scaffold

Cross-platform privacy-hardening program. Two-layer product:
- SilverLABS Application Stack (cross-platform spine)
- Platform Hardening Profiles (per-OS, tier-honest)

Platforms: Linux (Debian/Kicksecure), Android (Pixel/Samsung/Moto/generic),
Windows (LTSC IoT), macOS (profile), iOS (MDM profile). Each flavour has
both a preflashed hardware SKU path and a self-apply "harden your existing
device" path.

Includes umbrella docs (README + threat-model, design-principles,
platform-matrix, roadmap, trust-model), per-platform and per-stack-
component README stubs, .gitignore, LICENSE.

Linux v1 ships first; Stack v1 = Browser + VPN + Sync.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,67 @@
+# Build outputs
+build/output/
+build/cache/
+*.iso
+*.img
+*.deb
+*.rpm
+*.exe
+*.msi
+*.dmg
+*.pkg
+*.apk
+*.aab
+*.ipa
+
+# Secrets / keys (real keys never live in this repo)
+*.key
+*.pem
+*.p12
+*.pfx
+*.gpg
+secring.*
+*-private*
+*.kbx
+trustdb.gpg
+
+# OS / editor cruft
+.DS_Store
+Thumbs.db
+*~
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# Local config overrides
+*.local
+.env
+.env.*
+!.env.example
+
+# Toolchain caches
+node_modules/
+__pycache__/
+*.pyc
+.cache/
+.npm/
+target/
+obj/
+bin/
+dist/
+out/
+
+# Live-build / debootstrap intermediates
+chroot/
+binary/
+*.log
+.build/
+config/local-*
+
+# Test artifacts
+tests/output/
+*.cov
+coverage/
+
+# SBOM intermediates (final SBOMs are committed; intermediates are not)
+sbom/work/