chore(1000.yaml): add Fourier's theorem (#29047)

Mathlib has some form of it already; while there is space for more advanced versions, let's surface the current progress already.

Author: grunweg

docs/1000.yaml

@@ -80,6 +80,12 @@ Q179208:
 
 Q179467:
   title: Fourier theorem
+  decls:
+    - MeasureTheory.Integrable.fourier_inversion
+    - Continuous.fourier_inversion
+  authors: Sébastien Gouezel
+  date: 2024
+  comment: "The wikipedia page is really vague; it's not clear what is meant here. While mathlib has some material already, there is space for more advanced results."
 
 Q179692:
   title: Independence of the axiom of choice