docs: add Trident framework architecture overview

[joan-bisbal]

Adds a high-level architecture overview for new contributors: the ingest -> decode -> persist -> serve pipeline, what each service owns, and how PostgreSQL and Redis divide responsibility between durable history and real-time fan-out.

Includes a mermaid diagram of the full data path from Soroban RPC through to REST/gRPC/WebSocket clients.

No code changes -- documentation only.

[Depo-dev]

The PR is titled "add Trident framework architecture overview", but this is a three-line file whose entire body restates the title. An architecture overview needs to actually describe the architecture: the indexer -> Postgres -> Redis -> gRPC API -> Go REST API pipeline, where the crates in crates/ and services in services/ sit in it, and how events flow from Soroban RPC through to /v1/events and the WebSocket/SSE streams.

There is real material to draw on: README.md, docs/deployment.md, and docs/ENVIRONMENT.md already document parts of this, and crates/indexer/src/streamer/mod.rs is the core of the ingest path.

Also: please target dev rather than main (all feature work lands on dev), and drop the UTF-8 BOM at the start of the file — no other file in docs/ has one.

A genuine overview would be a welcome addition, so please do resubmit with actual content.

[Depo-dev]

Hey @joan-bisbal — this is the best of the three docs PRs. The title is right, the mermaid diagram matches the actual service topology, and the component breakdown lines up with what's really in crates/ and services/. I checked it against the tree rather than taking it on faith and it holds up.

Two small things before I merge.

The description is one line, and it's doing less than it could. A reader landing on this PR can't tell what's covered or why it exists. Something like:

Adds a high-level architecture overview for new contributors: the ingest → decode → persist → serve pipeline, what each service owns, and how PostgreSQL and Redis divide responsibility between durable history and real-time fan-out.

Includes a mermaid diagram of the full data path from Soroban RPC through to REST/gRPC/WebSocket clients.

No code changes — documentation only.

Second, a naming nit: everything else in docs/ uses kebab-case (soroban-event-model.md, indexer-event-filtering.md, stream-events.md), and this one is trident_architecture_overview.md. Could you rename it to docs/trident-architecture-overview.md so it doesn't stand out?

Both are quick. Once they're in I'll merge this one.

[joan-bisbal]

Thanks for the review. Both changes done:

• Renamed trident_architecture_overview.md to trident-architecture-overview.md to match the kebab-case convention in docs/
• Updated the PR description as suggested

Ready for re-review.