Enable type-aware linting in ui-tui-opentui-v2: add projectService +
tsconfigRootDir to the TS files block and switch the preset to
recommendedTypeChecked. Turn ON as ERROR the high-value promise rules
(no-floating-promises, no-misused-promises, await-thenable) and fix the
3 real floating-promise sites in the gateway client (FileSink
write/flush/end are fire-and-forget on a piped child stdin — marked
with explicit `void`).
Defer the cast/unknown family + the noisy type-checked rules to 'warn'
(gate stays green; eslint exits 0 on warnings) for Phase 2, which will
replace the `as`/`unknown` boundary casts with Schema decoding:
no-unsafe-{assignment,member-access,argument,return,call},
no-unnecessary-condition, no-base-to-string, restrict-template-
expressions, no-unnecessary-type-assertion, require-await.