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/img/spin.svg

@@ -0,0 +1,34 @@
+<svg xmlns="http://www.w3.org/2000/svg" class="o_spinner" viewBox="0 0 50 50" width="50" height="50">
+    <style>
+        @keyframes dash {
+            0% {
+                stroke-dashoffset: 120;
+                stroke-width: 2px;
+            }
+            35%, 50% {
+                stroke-dashoffset: 0;
+                stroke-width: 8px;
+            }
+            85%, 100% {
+                stroke-dashoffset: -120;
+                stroke-width: 2px;   
+            }
+        }
+        @keyframes rotate {
+            0% {
+                transform: rotate(0deg);
+            }
+            100% {
+                transform: rotate(360deg);
+            }
+        }
+        svg {
+            animation: rotate 1s linear infinite;
+        }
+        circle {
+            stroke-dasharray: 120, 120;
+            animation: dash 2.5s ease infinite;
+        }
+    </style>
+    <circle cy="25" cx="25" r="19" stroke="#fff" stroke-width="2" fill="none" stroke-linecap="round"/>
+</svg>