Initial commit: NexusOS project + desktop theme baseline

Captures the known-good state after theme consolidation and
consistency reconciliation:
- NexusOS GTK/xfwm4/icon theme assets (assets/themes, management/Mint-Y-Nexus)
- Tightened right-click menus, visible separators, no menu icons
- assets/themes/install-theme.sh: idempotent restore of all wiring
  (symlinks, xfconf xsettings+xfwm4, GTK 3/4 settings.ini)
- .gitignore excludes venv/ollama/models/runtime/db

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,30 @@
+# Large machine-specific / regenerable trees (never commit)
+# Promethean/ = 16G ROCm venv (recreate from requirements*.txt)
+# ollama/ = 7.4G bundled Ollama binary; models/ = 4.9G Ollama blobs
+Promethean/
+ollama/
+models/
+interface/web/node_modules/
+
+# Runtime state & user data
+runtime/
+data/uploads/
+data/exports/
+*.db
+*.db-wal
+*.db-shm
+
+# Build / cache artifacts
+interface/web/dist/
+__pycache__/
+*.pyc
+*.pyo
+
+# Editor / DE / local cruft
+.directory
+*.bak
+*.bak-*
+*.tar.gz
+
+# Local-only Claude config (machine-specific)
+.claude/settings.local.json