Fix formatting in project structure section

[ABHIRAM-CREATOR06]

What does this PR do?

A clear, specific description. Not "fixes bug" — what was broken, what changed, why this approach.

Related issue

Closes #

Component(s) touched

• protocol/ — Signal Protocol implementation (X3DH, Double Ratchet)
• backend/ — server, auth, database
• frontend/ — UI
• simulator/ — protocol explainer
• tests/
• Docs (README.md, specification_docs/, etc.)
• CI / build

Is this security-relevant?

• Yes — touches key handling, session state, auth, or anything affecting forward secrecy / post-compromise security
• No

If yes: does this address a known threat from datathreat.md? Which one (e.g. T-07)? If it's a new issue not yet documented there, say so explicitly — don't let a security-relevant change land without the threat model catching up.

How was this tested?

• npm test passes locally
• npm run test:x25519 passes locally
• Added or updated a test for this change
• Manually tested (describe how below)

Describe manual testing if applicable:

Checklist

• Code uses tabs, not spaces (matches existing style)
• No secrets, .db files, or key material committed (check git status against .gitignore)
• Updated the relevant API/WebSocket table in README.md if an endpoint or message type changed
• Commit messages follow type(scope): description convention

Anything else reviewers should know?

Tradeoffs made, things you're unsure about, follow-up work you're deliberately leaving out of scope.