fix(scripts): SIGPIPE-safe first-line selection in 5 scripts

[yasinBursali]

What

Replace | head -1 | / | head -n 1 | with | sed -n '1p' | in five scripts to eliminate SIGPIPE termination under set -euo pipefail.

Why

head -1 closes its stdin after consuming one line. When the upstream pipeline stage produces multiple lines (multi-GPU nvidia-smi output, multiple GGUFs, duplicate .env keys), the resulting SIGPIPE (exit 141) propagates back through the pipeline and — because all five files run under set -euo pipefail — aborts the script entirely. The three distinct trigger conditions are:

• Multi-GPU NVIDIA host: nvidia-smi --query-gpu=... emits one line per GPU. pre-download.sh (VRAM detection) and dream-preflight.sh (GPU probe) both abort on the SIGPIPE.
• Multiple GGUFs present: ls -1 data/models/*.gguf on a host with 2+ downloaded models causes check-offline-models.sh to abort before reporting status.
• Duplicate key in .env: grep returns multiple matches; read_env_value (dream-macos.sh + env-generator.sh) and read_searxng_secret (env-generator.sh) silently return empty strings — the || true guard prevents script abort but leaves the variable empty/truncated.

How

Six targeted substitutions across 5 files:

File	Line	Change
dream-server/scripts/pre-download.sh	112	head -1 → sed -n '1p'
dream-server/scripts/dream-preflight.sh	87	head -1 → sed -n '1p'
dream-server/scripts/check-offline-models.sh	27	head -1 → sed -n '1p'
dream-server/installers/macos/dream-macos.sh	158	head -n 1 → sed -n '1p'
dream-server/installers/macos/lib/env-generator.sh	39	head -n 1 → sed -n '1p'
dream-server/installers/macos/lib/env-generator.sh	51	head -n 1 → sed -n '1p'

sed -n '1p' consumes the full stdin stream before exiting, so the upstream producer never receives SIGPIPE. It is identical in behaviour on BSD sed (macOS) and GNU sed (Linux).

Testing

• Automated: bash -n syntax check passes on all 5 files. ShellCheck: no new warnings introduced.
• Manual (Linux NVIDIA multi-GPU): Run dream-server/scripts/pre-download.sh and dream-server/scripts/dream-preflight.sh on a host with 2+ GPUs — both should complete without SIGPIPE exit 141.
• Manual (macOS, multiple GGUFs): Place 2+ .gguf files in data/models/ and run dream-server/scripts/check-offline-models.sh — should enumerate correctly.
• Manual (macOS, duplicate .env key): Add a duplicate key to .env and run through the macOS installer read_env_value path — should return the first value, not empty.

Platform Impact

• macOS: Affected — dream-macos.sh and env-generator.sh fixes apply here only.
• Linux (NVIDIA): Affected — pre-download.sh and dream-preflight.sh fixes apply to multi-GPU NVIDIA hosts.
• Linux (AMD/CPU): check-offline-models.sh fix applies to any platform with 2+ GGUFs.
• Windows (WSL2): Not directly affected — these scripts run on the Linux / macOS side. WSL2 inherits Linux behaviour if any of these scripts are invoked there.

Known Considerations

None — mechanical substitutions only; no logic changes.