Add startup check for required indexer feature flags

[aniokedianne]

Summary
Add startup check for required indexer feature flags

Scope

• validate required indexer feature flags at startup\n- fail fast with actionable error output on invalid config\n- keep check centralized in bootstrapping flow

Acceptance Criteria

• scoped change is implemented with no unrelated file churn
• docs/tests are updated where applicable
• contributor can validate the outcome locally

Contributor coordination: if you pick this up, reach out in Telegram for updates or clarification: https://t.me/accesslayerorg

[AlphaTechini]

@AlphaTechini has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I will love to handle this issue.

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

[temisan0x]

@temisan0x has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hi Maintainer! I'd love to take on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @temisan0x to this issue.

[dinahmaccodes]

@dinahmaccodes has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hi, please can I be assigned this
I will do it quickly and the code will pass as expected

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

[Stanley-Owoh]

@Stanley-Owoh has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Good day maintainer
How are you doing please I would like to work on this issue please assign it to me I can work on this and give you positive results
Thank you

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

[davedumto]

@davedumto has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

i would like to work on this

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

[drips-wave]

Congratulations, @davedumto! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @davedumto: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊