Web Client: Integrate Matrix Rust SDK

Goal:

Prepare the postbox Web client project to use the Matrix Rust SDK. The application should be able to send and receive a message.

Acceptance Criteria:

• Clarify maintenance of the following points:
  • https://github.com/matrix-org/matrix-rust-sdk/pull/5127 → Contract with Filament needs to be signed.
  • https://github.com/jhugman/uniffi-bindgen-react-native → Community maintained. Is that enough?
  • https://github.com/element-hq/aurora/tree/hackdays2025/src/generated  → Commitment from Element, but no timeline yet (split out into a package!).
• The Matrix Rust SDK bindings are part of the project and the build process
• There is minimal UI (ie, console log-type messages in a visible window)

Notes:

How to test the message exchange? It needs another account. Use an echo bot? Deploy a full matrix stack with the test or use some env?

Update:

• we expect a disposable homeserver + accounts (k8s namespace) to run via CI
  • this a blocker for this ticket
  • see #173

Risks:

The effort to setup another account to have an exchange with.

Notes/ resources:

Requirements uIDs: Zapuk_14; Zapuk_16; Zapuk_19; Zapuk_22; Zapuk_28