install-hailo.sh assumes a clean machine: detect a pre-existing upstream hailo-ollama before installing

[jaylfc]

Found while a community tester (@doc62fr) worked through #1771 on real hardware, a Raspberry Pi 5 with an AI HAT+2. Nobody on the team has this hardware, so this only surfaced because he is testing it.

The gap

scripts/install-hailo.sh assumes a clean machine. It does not check whether hailo-ollama is already installed and running from Hailo's own route (their installer, a desktop shortcut, or a manual build).

In the reported case the tester had upstream hailo-ollama serving on 0.0.0.0:8000, which is its default. Our script remaps to 7836 by setting Environment=OLLAMA_HOST=127.0.0.1:7836 in the unit it installs, so the two coexist invisibly: a working server on 8000 that taOS cannot see, no hailo-ollama.service, and nothing on 7836. From the user's side taOS simply appears broken while their Hailo setup works fine, which is a confusing place to leave someone.

What it should do

Before installing, detect a pre-existing upstream instance (something listening on 8000 that answers /api/tags, or an existing binary/service not installed by us) and then either:

1. Adopt it: reconfigure the existing install to the taOS port and manage it under hailo-ollama.service, or
2. Say so plainly: report what was found, what will change, and what will be left alone, before touching anything.

Silently building a second server alongside the first is the one behaviour to avoid, since both then compete for the accelerator.

Notes

• Port 7836 is correct and should stay. 8000 is the Django slot in taOS port hygiene and is already probed as a llama-cpp/vllm candidate, so leaving Hailo there makes those probes ambiguous.
• The same class of check probably applies to the other backend installers (rkllama in particular), which have the same greenfield assumption. Worth checking rather than fixing this one in isolation.
• Related: Pi 5 + Hailo-10H (AI HAT+2, 40 TOPS): wire the hailo-genai LLM backend (community help wanted) #1771 (the Hailo backend slice), App install: don't bind core ports (80/443/8080/...) — allocate randomized ports + remap apps that default to them #695 (app port hygiene).