fix(demo-offline): handle EOF cleanly during menu and pause prompts

[vaibhavsrv]

Why this matters

In ods/scripts/demo-offline.sh, the interactive showcase menu and intermediate pause functions use read -r choice and read -r under set -e. When executed in automated testing harnesses, piped streams, or headless environments where standard input is closed (</dev/null), read returns a non-zero exit status on EOF. Because set -e is active, this unexpected return code abruptly terminates the script with exit code 1 instead of exiting cleanly with 0.

This patch updates pause() to allow non-zero returns (read -r || true) and modifies the menu loop to exit cleanly with code 0 upon encountering EOF on read -r choice.

Validation

• Repro baseline: Executed bash demo-offline.sh </dev/null; confirmed script aborted with exit code 1.
• Post-fix: Verified test_demo_offline_eof.py passes with exit code 0; demo-offline.sh renders header and exits 0 on EOF or explicit quit.
• Demo suites: 2 passed. New-test Ruff, ShellCheck, and diff checks pass; new regressions wired into Linux CI.

Overlap check

• fix(env): probe .env keys literally in _env_set and mode-switch env_set #5819 (0xacee): Addressed macOS environment generation and safe escaping; touches ods/installers/macos/ with zero overlap in demo scripts.
• fix(cold-storage): create cold directory before archiving idle models #5861 (vaibhavsrv): Addressed directory creation in cold storage archiving; touches ods/scripts/llm-cold-storage.sh.
• fix(scripts): validate context length, port bounds, and control characters in render-runtime-configs #5056 (upstream): Touched Compose model definitions without altering demo utilities.

Risk / AI disclosure

AI-assisted investigation, implementation and CLI regressions. This strengthens input EOF handling in the offline demonstration script, not runtime core services. Independent human review and platform/runtime qualification remain gates. No running configuration, deployment or upstream merge changed.

Follow-up integration evidence

Composed with #5861 at 2a24f49 without conflicts. Production and test diffs passed together; demo and showcase contracts remain intact.
Backlog composition was local-only (production/test diffs, excluding workflow/Makefile wiring); it is not an upstream merge or independent human approval. Declared live-review gates remain open.

[Lightheartdevs]

Thanks for this contribution. public-beta was promoted into main on 2026-09-24 and no longer receives changes, so we're closing pull requests that target it. This isn't a judgment on the change itself. If it's still needed, please rebase onto main and open a focused PR. See #7253 for details and the contribution policy.