Icon Request: sine_wave

**Icon Proposal: sine_wave**
Sine waves are a ubiquitous symbol that can indicate sound or vibration, electromagnetic waves like light, alternating current, and many more. There is also no single wave that I could find, all being stacked or multiple waves, or having some extra feature. In addition, all of these waves aren't sine waves, but rather sine-like waves - and when I've used them, the ambiguity has backfired. A dedicated icon would help apps as well as presentations and other visual media that need to communicate these or many related concepts effectively and precisely.

**Description**
The curve y=sin(x), over the domain [0, 2pi], with an offset/parallel curve below it for thickness.
Note that the offset curve can either be offset exclusively below, letting the top line be a sine wave, or it could be below and above, letting the middle line be a sine wave; for ease of use I would prefer the first one, but it depends entirely on your style guide.

**See Also**
- Google Material Icons `airwave` and `waves`, the most similar to the proposed symbol
- Unicode character: U+223F (although hopefully what you produce is much closer to a sine wave than this!)

**Similar Existing Icons**
- `airwave` - three stacked waves, similar to sine waves but not quite. Does not represent one period of the wave, and the three stacked makes it ambiguous when I've tried to use it.
- `waves` - Same issue as above.
- `heat` - three horizontal waves, same issue as above.

**Concept Sketch**
I know that Google is NOT accepting finished SVGs for inclusion. This is NOT a finished SVG, it is a concept sketch as to what I am envisioning with this icon. I really hope this is acceptable.

I'd really love if this icon could make it in, it'd mean a lot to me. I know you probably don't check these very much, and my suggestion is very unlikely to make it into Material Symbols - but, it would be very helpful if it was. Thank you in advance.

PS: When you add new symbols, do you update the Google Slides/Docs/etc font "MATERIAL SYMBOLS" to contain the new symbols? If so, is this process automatic, and how long does it take? Just wondering, thanks!

Review the existing `airwave`, `waves`, and `heat` symbols alongside the attached concept sketch. Check the repository's icon contribution and style guidance before determining whether the proposed one-period sine wave fits the icon set. Done means the proposal has been evaluated or implemented consistently with the project's visual standards.

Written by the indexing model from the issue text.