fix(cua-driver): preserve embedded telemetry preference

[injaneity]

summary

• preserve CUA_DRIVER_RS_TELEMETRY_ENABLED when an SDK-owned embedded host builds the private daemon environment
• preserve the supported CUA_TELEMETRY_ENABLED compatibility name as well
• cover inherited preferences and explicit host-option overrides

why

EmbeddedCuaDriverHost clears the child environment and restores an allowlisted subset. Both supported Cua Driver telemetry settings were missing from that allowlist, so embedding hosts could not carry their telemetry preference into the private daemon. Passing either name through EmbeddedDriverHostOptions.environment also failed because explicit overrides use the same filter.

This is the first focused fix found while evaluating replacement of downstream private-daemon lifecycle code with the SDK-owned host. Overlay controls and stderr diagnostics remain separate focused changes in the dependent PRs. Host-process ownership remains unchanged.

Closes #3276.

validation

• cargo fmt --all -- --check
• cargo test --locked -p cua-driver-sdk — 52 passed
• git diff --check

The macOS linker emitted the existing duplicate Swift symbol warnings; the test suite passed. No desktop E2E is required because this change only modifies the SDK child-environment allowlist and has deterministic unit coverage.

[f-trycua]

Approved after exact-head review. The change is narrowly scoped to the embedded child-environment allowlist, preserves both supported telemetry variables, and covers inherited plus explicit override behavior. All required checks are green; no desktop E2E is needed for this deterministic environment-filter change.