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/_ratio.scss

@@ -0,0 +1,26 @@
+// Credit: Nicolas Gallagher and SUIT CSS.
+
+.ratio {
+  position: relative;
+  width: 100%;
+
+  &::before {
+    display: block;
+    padding-top: var(--#{$prefix}aspect-ratio);
+    content: "";
+  }
+
+  > * {
+    position: absolute;
+    top: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+  }
+}
+
+@each $key, $ratio in $aspect-ratios {
+  .ratio-#{$key} {
+    --#{$prefix}aspect-ratio: #{$ratio};
+  }
+}