Eliminate Python dependency: embed frontend assets in odoo-go

- Copy all OWL frontend assets (JS/CSS/XML/fonts/images) into frontend/
  directory (2925 files, 43MB) — no more runtime reads from Python Odoo
- Replace OdooAddonsPath config with FrontendDir pointing to local frontend/
- Rewire bundle.go, static.go, templates.go, webclient.go to read from
  frontend/ instead of external Python Odoo addons directory
- Auto-detect frontend/ and build/ dirs relative to binary in main.go
- Delete obsolete Python helper scripts (tools/*.py)

The Go server is now fully self-contained: single binary + frontend/ folder.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/web/static/lib/bootstrap/scss/_mixins.scss

@@ -0,0 +1,42 @@
+// Toggles
+//
+// Used in conjunction with global variables to enable certain theme features.
+
+// Vendor
+@import "vendor/rfs";
+
+// Deprecate
+@import "mixins/deprecate";
+
+// Helpers
+@import "mixins/breakpoints";
+@import "mixins/color-mode";
+@import "mixins/color-scheme";
+@import "mixins/image";
+@import "mixins/resize";
+@import "mixins/visually-hidden";
+@import "mixins/reset-text";
+@import "mixins/text-truncate";
+
+// Utilities
+@import "mixins/utilities";
+
+// Components
+@import "mixins/backdrop";
+@import "mixins/buttons";
+@import "mixins/caret";
+@import "mixins/pagination";
+@import "mixins/lists";
+@import "mixins/forms";
+@import "mixins/table-variants";
+
+// Skins
+@import "mixins/border-radius";
+@import "mixins/box-shadow";
+@import "mixins/gradients";
+@import "mixins/transition";
+
+// Layout
+@import "mixins/clearfix";
+@import "mixins/container";
+@import "mixins/grid";