Fix broken image URLs in documentation (issue malariagen#1247)

- Replace external CDC and Wikimedia image URLs with local copies
- Store images in docs/source/_static/images/
- Update docs/source/index.rst with relative image paths
- Verify documentation builds without errors
- All tests pass

Author: Yashsingh045

docs/source/_static/images/anopheles_dirus.jpg

@@ -17,31 +17,43 @@ API documentation
 
       *Anopheles gambiae* complex.
 
-      .. image:: https://upload.wikimedia.org/wikipedia/commons/0/0a/AnophelesGambiaemosquito.jpg
+      .. image:: ./_static/images/anopheles_gambiae.jpg
+         :alt: Anopheles gambiae mosquito
+         :align: center
+         :width: 100%
 
    .. grid-item-card:: ``Af1``
       :link: Af1
       :link-type: doc
 
       *Anopheles funestus* subgroup.
 
-      .. image:: https://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Anopheles_Funetus.jpg/640px-Anopheles_Funetus.jpg
+      .. image:: ./_static/images/anopheles_funestus.jpg
+         :alt: Anopheles funestus mosquito
+         :align: center
+         :width: 100%
 
    .. grid-item-card:: ``Amin1``
       :link: Amin1
       :link-type: doc
 
       *Anopheles minimus*.
 
-      .. image:: https://upload.wikimedia.org/wikipedia/commons/thumb/1/11/Anopheles_minimus_1.jpg/640px-Anopheles_minimus_1.jpg
+      .. image:: ./_static/images/anopheles_minimus.jpg
+         :alt: Anopheles minimus mosquito
+         :align: center
+         :width: 100%
 
    .. grid-item-card:: ``Adir1``
       :link: Adir1
       :link-type: doc
 
       *Anopheles dirus* complex.
 
-      .. image:: https://phil.cdc.gov//PHIL_Images/8777/8777_lores.jpg
+      .. image:: ./_static/images/anopheles_dirus.jpg
+         :alt: Anopheles dirus mosquito
+         :align: center
+         :width: 100%
 
 Documentation for the `Pf7 <https://malariagen.github.io/parasite-data/pf7/api.html>`_ (*Plasmodium falciparum*)
 and `Pv4 <https://malariagen.github.io/parasite-data/pv4/api.html>`_ (*Plasmodium vivax*) APIs is also available,