Docs: timpani, saxophone, Part.roll(), update waveform counts

- Add timpani and saxophone synth sections to synths.rst
- Add rolls section to sequencing.rst with examples
- Update waveform count: 27 → 29

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/guide/sequencing.rst

@@ -620,6 +620,36 @@ Three bend types:
 - ``"late"`` — holds the starting pitch for 60%, bends in the last 40%.
   The classic blues "curl."
 
+Rolls
+-----
+
+Rapid repeated notes with a velocity ramp — perfect for timpani
+rolls, snare rolls, tremolo on any instrument. The velocity ramps
+from ``velocity_start`` to ``velocity_end`` for crescendo or
+decrescendo effects.
+
+.. code-block:: python
+
+   # Timpani crescendo roll
+   timp = score.part("timp", instrument="timpani")
+   timp.roll("C3", Duration.WHOLE, velocity_start=20, velocity_end=110)
+   timp.add("C3", Duration.HALF, velocity=127)  # big accent
+
+   # Snare roll with 32nd notes
+   snare = score.part("snare", synth="noise", envelope="pluck")
+   snare.roll("C4", Duration.HALF, speed=0.125,
+              velocity_start=40, velocity_end=100)
+
+   # Decrescendo (loud to quiet)
+   timp.roll("G2", Duration.WHOLE, velocity_start=100, velocity_end=30)
+
+Parameters:
+
+- ``velocity_start``: Starting velocity (default 40).
+- ``velocity_end``: Ending velocity (default 100).
+- ``speed``: Note subdivision (default ``Duration.SIXTEENTH``).
+  Use ``0.125`` for 32nd notes, ``Duration.EIGHTH`` for 8th notes.
+
 Tuning Systems
 --------------
 

docs/guide/synths.rst

@@ -1,7 +1,7 @@
 Synthesizers
 ============
 
-PyTheory includes 27 built-in waveforms and 10 ADSR envelope presets.
+PyTheory includes 29 built-in waveforms and 10 ADSR envelope presets.
 Every sound is generated from scratch -- no samples or external audio
 files needed.
 
@@ -390,11 +390,11 @@ Dedicated Instrument Synths
 --------------------------
 
 Beyond the classic and physical modeling waveforms, PyTheory includes
-14 dedicated instrument synths. Each one uses tailored synthesis
+16 dedicated instrument synths. Each one uses tailored synthesis
 techniques -- additive harmonics, formant shaping, body resonance
 modeling, and specialized envelopes -- to capture the character of a
 specific acoustic instrument. These are the waveforms that bring the
-total count to 27.
+total count to 29.
 
 Piano Synth
 ~~~~~~~~~~~
@@ -535,6 +535,29 @@ bridge, producing a shimmering, metallic sustain.
 
    sitar = score.part("sitar", synth="sitar_synth")
 
+Timpani Synth
+~~~~~~~~~~~~~
+
+Large kettle drum with definite pitch. Inharmonic membrane modes
+(1.0, 1.5, 1.99, 2.44), felt mallet attack, copper kettle resonance.
+Use ``Part.roll()`` for crescendo timpani rolls.
+
+.. code-block:: python
+
+   timp = score.part("timp", synth="timpani_synth")
+   timp.roll("C3", Duration.WHOLE, velocity_start=20, velocity_end=110)
+
+Saxophone Synth
+~~~~~~~~~~~~~~~
+
+Single reed through a conical brass bore. All harmonics with strong
+mids, reed buzz, and brass body warmth. Four presets: ``saxophone``,
+``alto_sax``, ``tenor_sax``, ``bari_sax``.
+
+.. code-block:: python
+
+   sax = score.part("sax", instrument="tenor_sax")
+
 Analog Oscillator Drift
 ~~~~~~~~~~~~~~~~~~~~~~~~