Final review: fix remaining terminology issues

- doc/api/index.rst: "Plotting figure elements" → "Plotting embellishments" (consistent with gallery and techref usage)
- pygmt/src/image.py: "plot it on a plot" → "plots it" (fix awkward phrasing)
- pygmt/tests/test_image.py: "Place images on map" → "Place images on the figure"
- pygmt/tests/test_subplot.py: "map frame setting" → "plot frame setting", "all subplot figures" → "all subplot panels", "Plot map elements" → "Plot elements"

Agent-Logs-Url: https://github.com/GenericMappingTools/pygmt/sessions/ec6d8067-efa4-4bd0-ad87-85456d70041c

Co-authored-by: seisman <3974108+seisman@users.noreply.github.com>

Author: Copilot

doc/api/index.rst

@@ -18,8 +18,8 @@ All plotting is handled through the :class:`pygmt.Figure` class and its methods.
 
     Figure
 
-Plotting figure elements
-~~~~~~~~~~~~~~~~~~~~~~~~
+Plotting embellishments
+~~~~~~~~~~~~~~~~~~~~~~~
 
 .. autosummary::
     :toctree: generated

pygmt/src/image.py

@@ -39,7 +39,7 @@ def image(  # noqa: PLR0913
     r"""
     Plot raster or EPS images.
 
-    Reads an Encapsulated PostScript file or a raster image file and plot it on a plot.
+    Reads an Encapsulated PostScript file or a raster image file and plots it.
     The image can be scaled arbitrarily, and 1-bit raster images can be:
 
     - inverted, i.e., black pixels (on) become white (off) and vice versa.

pygmt/tests/test_image.py

@@ -11,7 +11,7 @@
 @pytest.mark.mpl_image_compare
 def test_image():
     """
-    Place images on map.
+    Place images on the figure.
     """
     fig = Figure()
     fig.image(imagefile="@circuit.png")

pygmt/tests/test_subplot.py

@@ -12,8 +12,8 @@
 @pytest.mark.mpl_image_compare
 def test_subplot_basic_frame():
     """
-    Create a subplot figure with 1 vertical row and 2 horizontal columns, and ensure map
-    frame setting is applied to all subplot figures.
+    Create a subplot figure with 1 vertical row and 2 horizontal columns, and ensure plot
+    frame setting is applied to all subplot panels.
     """
     fig = Figure()
 
@@ -28,7 +28,7 @@ def test_subplot_basic_frame():
 @pytest.mark.mpl_image_compare
 def test_subplot_direct():
     """
-    Plot map elements to subplot directly using the panel parameter.
+    Plot elements to subplot directly using the panel parameter.
     """
     fig = Figure()