Rust SDK for Canton Network #407 - Milestone 2: Codegen via daml-lf-archive (SCU-aware) + dpm component

Milestone 2: Codegen via daml-lf-archive (SCU-aware) + dpm component

• Estimated delivery: Month 3 · Hard deadline: 4 months from grant approval.
• Estimated effort: ~65 person-days (the heaviest engineering milestone).
• Deliverables:

- canton-codegen generating typed Rust from DARs through daml-lf-archive, SCU/PackageMap-aware, covering templates, choices, interfaces, and contract keys, with JSON and gRPC codecs on the generated types. - dpm codegen-rust component integration. - Documented Daml-LF → Rust type mapping; first canton-splice-* reference crates; sample app using generated bindings.

• Verification: demonstrate codegen → submit command → observe transaction → query ACS on both gRPC and JSON paths; an SCU version bump regenerates compatible code.

| Milestone | Payment | % of total | |---|---|---| | M2 — Codegen (daml-lf-archive, SCU) + dpm component | 150,000 CC upon committee acceptance | ~11.5% |

_Originally posted by @pedrodneves in https://github.com/canton-foundation/canton-dev-fund/issues/407#issuecomment-4979835872_