docs(manim-video): expand references with Manim CE API coverage and 3b1b production patterns

[SHL0MS]

Summary

Expands the manim-video skill references with 601 lines of new content sourced from deep review of the Manim CE v0.20.1 reference manual, 3b1b/manim source code, Grant's production workflow (3b1b/videos CLAUDE.md), and Manim CE thematic guides.

What was added

animations.md (+135 lines)

• always_redraw() — reactive mobjects that auto-rebuild each frame
• TracedPath — trajectory tracing with dissipating trails
• FadeTransform / TransformFromCopy — smoother cross-fades, recommended over Transform for dissimilar shapes
• ApplyMatrix — linear transformation visualization
• squish_rate_func — time-window staggering within AnimationGroup
• ShowIncreasingSubsets / ShowSubmobjectsOneByOne — progressive reveals for algorithm visualization
• ShowPassingFlash — light traveling along a path
• Expanded rate functions: running_start, there_and_back_with_pause, not_quite_there

mobjects.md (+158 lines)

• SVGMobject / ImageMobject — external asset import
• Variable — auto-updating labeled value display
• BulletedList — convenience text mobject
• DashedLine, Angle, RightAngle — geometry markers
• Boolean operations (Union, Intersection, Difference, Exclusion)
• LabeledArrow / LabeledLine — auto-positioned labels
• t2c / t2f / t2s / t2w — per-substring color/font/slant/weight (from 3b1b patterns)
• Backstroke for text readability over backgrounds
• apply_complex_function with prepare_for_nonlinear_transform()

equations.md (+85 lines)

• substrings_to_isolate for complex equations (QED Lagrangian pattern)
• Multi-line equations with per-line animation
• TransformMatchingTex with matched_keys and key_map (from 3b1b's TexTransformExample)
• set_color_by_tex for substring coloring

graphs-and-data.md (+72 lines)

• Graph / DiGraph with layout algorithms (spring, circular, tree, etc.)
• ArrowVectorField / StreamLines for physics/math vector field visualization
• ComplexPlane / PolarPlane specialized coordinate systems

camera-and-3d.md (+59 lines)

• ZoomedScene — inset zoom with magnification box
• LinearTransformationScene — pre-built 3b1b-style linear algebra scenes with basis vectors and grid deformation

rendering.md (+92 lines)

• manim.cfg project-level configuration file
• self.next_section() chapter markers with --save_sections rendering
• manim-voiceover plugin — official TTS integration with ElevenLabs/GTTS/Azure, auto-sync via tracker.duration and bookmark-based timing

Sources

All content verified against Manim CE v0.20.1 API. Patterns sourced from:

• Manim CE Reference Manual
• 3b1b/manim example_scenes.py
• 3b1b/videos CLAUDE.md (production workflow)
• Manim CE Voiceover Guide