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/_spinners.scss

@@ -0,0 +1,85 @@
+//
+// Rotating border
+//
+
+.spinner-grow,
+.spinner-border {
+  display: inline-block;
+  width: var(--#{$prefix}spinner-width);
+  height: var(--#{$prefix}spinner-height);
+  vertical-align: var(--#{$prefix}spinner-vertical-align);
+  // stylelint-disable-next-line property-disallowed-list
+  border-radius: 50%;
+  animation: var(--#{$prefix}spinner-animation-speed) linear infinite var(--#{$prefix}spinner-animation-name);
+}
+
+// scss-docs-start spinner-border-keyframes
+@keyframes spinner-border {
+  to { transform: rotate(360deg) #{"/* rtl:ignore */"}; }
+}
+// scss-docs-end spinner-border-keyframes
+
+.spinner-border {
+  // scss-docs-start spinner-border-css-vars
+  --#{$prefix}spinner-width: #{$spinner-width};
+  --#{$prefix}spinner-height: #{$spinner-height};
+  --#{$prefix}spinner-vertical-align: #{$spinner-vertical-align};
+  --#{$prefix}spinner-border-width: #{$spinner-border-width};
+  --#{$prefix}spinner-animation-speed: #{$spinner-animation-speed};
+  --#{$prefix}spinner-animation-name: spinner-border;
+  // scss-docs-end spinner-border-css-vars
+
+  border: var(--#{$prefix}spinner-border-width) solid currentcolor;
+  border-right-color: transparent;
+}
+
+.spinner-border-sm {
+  // scss-docs-start spinner-border-sm-css-vars
+  --#{$prefix}spinner-width: #{$spinner-width-sm};
+  --#{$prefix}spinner-height: #{$spinner-height-sm};
+  --#{$prefix}spinner-border-width: #{$spinner-border-width-sm};
+  // scss-docs-end spinner-border-sm-css-vars
+}
+
+//
+// Growing circle
+//
+
+// scss-docs-start spinner-grow-keyframes
+@keyframes spinner-grow {
+  0% {
+    transform: scale(0);
+  }
+  50% {
+    opacity: 1;
+    transform: none;
+  }
+}
+// scss-docs-end spinner-grow-keyframes
+
+.spinner-grow {
+  // scss-docs-start spinner-grow-css-vars
+  --#{$prefix}spinner-width: #{$spinner-width};
+  --#{$prefix}spinner-height: #{$spinner-height};
+  --#{$prefix}spinner-vertical-align: #{$spinner-vertical-align};
+  --#{$prefix}spinner-animation-speed: #{$spinner-animation-speed};
+  --#{$prefix}spinner-animation-name: spinner-grow;
+  // scss-docs-end spinner-grow-css-vars
+
+  background-color: currentcolor;
+  opacity: 0;
+}
+
+.spinner-grow-sm {
+  --#{$prefix}spinner-width: #{$spinner-width-sm};
+  --#{$prefix}spinner-height: #{$spinner-height-sm};
+}
+
+@if $enable-reduced-motion {
+  @media (prefers-reduced-motion: reduce) {
+    .spinner-border,
+    .spinner-grow {
+      --#{$prefix}spinner-animation-speed: #{$spinner-animation-speed * 2};
+    }
+  }
+}