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/_alert.scss

@@ -0,0 +1,18 @@
+@include deprecate("`alert-variant()`", "v5.3.0", "v6.0.0");
+
+// scss-docs-start alert-variant-mixin
+@mixin alert-variant($background, $border, $color) {
+  --#{$prefix}alert-color: #{$color};
+  --#{$prefix}alert-bg: #{$background};
+  --#{$prefix}alert-border-color: #{$border};
+  --#{$prefix}alert-link-color: #{shade-color($color, 20%)};
+
+  @if $enable-gradients {
+    background-image: var(--#{$prefix}gradient);
+  }
+
+  .alert-link {
+    color: var(--#{$prefix}alert-link-color);
+  }
+}
+// scss-docs-end alert-variant-mixin