sync: Rise Rust v0.3.5

[jchen1]

Generated by .github/scripts/sync_rise.py.

Source

• Phoenix commit: 3343d458b9162061b4f810408bee2b14bcdf6af0

• Mode: automatic

• Synced paths:

• rise/rust -> rust

• rise/README.md -> README.md

• rise/instructions.json -> instructions.json

• rise/programs -> programs

• rise/test-fixtures -> test-fixtures

Changelog Draft

This draft was also appended to package changelog file(s) in this PR so it can be manually edited before merge:

• rust/CHANGELOG.md

### Summary

- `ix`: added `usdc_mint()`, an environment-aware USDC mint resolver that reads `PHOENIX_ENV` once (via `resolve_usdc_mint_for_env`) and returns `BETA_USDC_MINT` when set to `beta`, defaulting to the existing mainnet `USDC_MINT` otherwise.
- `ix`: added the new `BETA_USDC_MINT` constant for the beta deployment's USDC mint address.
- `core`, `cli`: internal call sites (`tx_builder`, `flight` command) now resolve the USDC mint via `usdc_mint()` instead of the static `USDC_MINT` constant, so transactions built through these paths follow `PHOENIX_ENV`.

### Breaking Changes

- None identified in the synced diff. `USDC_MINT` remains exported and still resolves to the mainnet address.

### Consumer Notes

- If your process may target the beta deployment, prefer calling `usdc_mint()` over the static `USDC_MINT` constant, and set `PHOENIX_ENV=beta` before first use — the resolved value is cached for the life of the process.
- No action needed for mainnet-only consumers; behavior and the `USDC_MINT` constant are unchanged.