fix: add type-aware routing for procedural flows

Centralizes tree navigation routing via getTreeNavigatePath helper.
Fixes all pages to route procedural sessions to /flows/:id/navigate
instead of /trees/:id/navigate. Adds safety redirect in troubleshooting
navigator and resume support in procedural navigator.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/schemas/tree.py

@@ -12,7 +12,7 @@ TreeType = Literal['troubleshooting', 'procedural']
 # --- Intake Form Schemas ---
 
 FIELD_TYPES = Literal[
-    'text', 'textarea', 'number', 'ip_address', 'email',
+    'text', 'textarea', 'number', 'ip_address', 'email', 'url',
     'select', 'multi_select', 'checkbox', 'password'
 ]