Add point-programmable vector commitments.

A commitment can be published before its hidden coordinate is chosen.
Opening one side of each aligned 1-bit DPF pair sets that coordinate or
the vector sum, and a shift moves it onto a public index.

Co-authored-by: Cursor <cursoragent@cursor.com>

doc/pages/introduction.md

@@ -21,6 +21,7 @@ zero-knowledge arguments, anonymous messaging, and more.
   - <i class="fa-solid fa-memory"></i> memoizers
   - <i class="fa-solid fa-file-lines"></i> json serialization
   - <i class="fa-solid fa-route"></i> asynchronous I/O
+  - <i class="fa-solid fa-fingerprint"></i> [point-programmable vector commitments](@ref ppvc_manual)
 
 ## Credits {#credits}