[Docs] Add JSDoc to buildDepositorYieldHistory in yieldHistoryService

[ogazboiz]

Telegram: https://t.me/+DOylgFv1jyJlNzM0

Why this matters

buildDepositorYieldHistory (backend/src/services/yieldHistoryService.ts, starting around line 150) is a 100+ line exported function that joins pool-level and depositor-level events, reconstructs share-price points, and returns a time series — but it has no doc comment. Other exports in the same file are documented; this one is the most complex and the hardest to onboard to. A JSDoc block describing parameters (address, _token, days, currentSharePrice), the returned YieldHistoryPoint[] shape, and the event types it reads would help contributors.

Acceptance criteria

• Add a JSDoc block above buildDepositorYieldHistory describing purpose, params, and return value
• Note why _token is currently unused (or document intended use)
• No behavioural changes

Files to touch

• backend/src/services/yieldHistoryService.ts

Out of scope

• Refactoring the function logic

[IyanuOluwaJesuloba]

@IyanuOluwaJesuloba has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hello Maintainer.

I am a full stack web3 developer with professional experience in software development, integration and smart contract writing.

I understand the criticality of this task, and I am confident that I will deliver accordingly.

I'd love to contribute my expertise to your project. Kindly assign this issue to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @IyanuOluwaJesuloba to this issue.

[luighis]

@luighis has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi 👋, I'm a front-end UI/UX developer with experience in Next.js, TypeScript, Shadcn, Zustand, Tailwind CSS, and more.

I've reviewed the requirements and I'd love to resolve this issue.
I actively contribute to several open-source projects and submit high-quality PR. 
The code will be clean, composable, and follow LabsCrypt conventions.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @luighis to this issue.

[wandooadzer-cmyk]

@wandooadzer-cmyk has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Can I work on this task?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @wandooadzer-cmyk to this issue.

[0xMegie]

@0xMegie has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Can I work on this sir...?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @0xMegie to this issue.