CA main and US main/distant signals (#673)

Base implementation for some tagged US and Canada main and distant
signals

Closes #653

This will need more work as the US and Canada establish tagging
guidelines.

### US

Around Chicago

(http://localhost:8000/#view=14.3/41.89746/-87.92877&style=signals):
<img width="1755" height="574" alt="image"
src="https://github.com/user-attachments/assets/afffbc16-86b7-4891-a45d-fc85028ea20a"
/>

(http://localhost:8000/#view=15.64/41.482924/-88.088233&style=signals):
<img width="804" height="905" alt="image"
src="https://github.com/user-attachments/assets/55cc3340-f3cd-4848-ae45-fcb612a0019b"
/>

(http://localhost:8000/#view=16.76/38.680231/-90.172901&style=signals):
<img width="854" height="560" alt="image"
src="https://github.com/user-attachments/assets/a058616e-0c8f-4b07-8d68-4e5e55bbe1a7"
/>



### Canada

(http://localhost:8000/#view=14.42/44.59721/-75.69216&style=signals):
<img width="797" height="562" alt="image"
src="https://github.com/user-attachments/assets/f65db79a-bc0d-4e95-a53c-94a2265fc419"
/>

Author: hiddewie

features/signals_railway_signals.yaml

@@ -1779,6 +1779,15 @@ features:
       - { tag: 'railway:signal:train_protection:form', value: 'sign' }
       - { tag: 'railway:signal:train_protection:type', value: 'end' }
 
+  # --- CA --- #
+
+  - description: Main signal
+    country: CA
+    icon: [ default: 'ca/main' ]
+    tags:
+      - { tag: 'railway:signal:main', value: 'CA:main' }
+      - { tag: 'railway:signal:main:form', value: 'light' }
+
   # --- CH --- #
 
   - description: Hauptsignal System L
@@ -7000,3 +7009,19 @@ features:
     tags:
       - { tag: 'railway:signal:stop', value: 'SE:Slutpunktstopplykta' }
       - { tag: 'railway:signal:stop:form', value: 'light' }
+
+  # --- US --- #
+
+  - description: Main signal
+    country: US
+    icon: [ default: 'us/main' ]
+    tags:
+      - { tag: 'railway:signal:main', any: ['US:main', 'US-ABS:main', 'US:GCOR:main'] }
+      - { tag: 'railway:signal:main:form', value: 'light' }
+
+  - description: Distant signal
+    country: US
+    icon: [ default: 'us/distant' ]
+    tags:
+      - { tag: 'railway:signal:distant', value: 'US:distant' }
+      - { tag: 'railway:signal:distant:form', value: 'light' }