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/_helpers.scss

@@ -0,0 +1,12 @@
+@import "helpers/clearfix";
+@import "helpers/color-bg";
+@import "helpers/colored-links";
+@import "helpers/focus-ring";
+@import "helpers/icon-link";
+@import "helpers/ratio";
+@import "helpers/position";
+@import "helpers/stacks";
+@import "helpers/visually-hidden";
+@import "helpers/stretched-link";
+@import "helpers/text-truncation";
+@import "helpers/vr";