chore(fleet): pin nixos-holochain to main after the lab merge

[Soushi888]

SoushAI analysis. Drafted by Soushi's AI assistant, reviewed and posted by @Soushi888.

No issue: first follow-up of #67 (listed in #67 (comment)).

What and why

The example fleet read nixos-holochain from lab/holoport-session because main did not carry the event profile and the Moss node. #67 merged that branch into main (merge commit 666c5ae), so the fleet goes back to main:

• examples/sensorica-fleet/flake.nix: nixos-holochain.url = "github:Sensorica/nixos-holochain", with the comment saying it is main, as a downstream fleet writes it.
• examples/sensorica-fleet/flake.lock: nix flake update nixos-holochain moved only that node, from 4b1b722 on the lab branch to 666c5ae on main. No other input changed.
• examples/sensorica-fleet/README.md (also the book's "The Sensorica Lab fleet" page): the Holoports install from main, and a Holoport installed from the lab branch switches its /etc/nixos-holochain checkout once, keeping its local operator key commit:

git -C /etc/nixos-holochain fetch origin
git -C /etc/nixos-holochain checkout -B main
git -C /etc/nixos-holochain rebase origin/main
git -C /etc/nixos-holochain branch --set-upstream-to=origin/main

checkout -B main names the current commit (key included) main; rebase origin/main replays only the operator key commit, since origin/lab/holoport-session is an ancestor of origin/main. After that, the existing git -C /etc/nixos-holochain pull --rebase follows main.

docs/deployment.md already clones the default branch, which is main, so it needed no change. No other file names the lab branch.

Commands run and what they printed

$ nix run nixpkgs#alejandra -- .
(no file changed)

$ nix flake check --no-build --all-systems
exit 0

$ cd examples/sensorica-fleet && nix flake check --no-build
checking derivation checks.x86_64-linux.eventProfileParity...
exit 0

$ for h in sensorica-holoport-0{1..5} workshop-iso; do nix eval --raw .#nixosConfigurations.$h.config.system.build.toplevel.drvPath; done
sensorica-holoport-01 /nix/store/l47sw8fhck4piz8l4645794dv01w9p66-nixos-system-sensorica-holoport-01-26.05.20260925.f5c082a.drv
sensorica-holoport-02 /nix/store/kmvjlnglvabyrrkl2nmrsvybs3clg2gk-nixos-system-sensorica-holoport-02-26.05.20260925.f5c082a.drv
sensorica-holoport-03 /nix/store/11540iizp9jz2m62ikvjxnxmnxvpxn7y-nixos-system-sensorica-holoport-03-26.05.20260925.f5c082a.drv
sensorica-holoport-04 /nix/store/dg58rvild6abb85ysy41bfzz1agihk2w-nixos-system-sensorica-holoport-04-26.05.20260925.f5c082a.drv
sensorica-holoport-05 /nix/store/a5n6cisb288pcn5hq1p1s6ynmmk0r0dz-nixos-system-sensorica-holoport-05-26.05.20260925.f5c082a.drv
workshop-iso          /nix/store/j2ipfyv1gafzp4l9198ns3s5f5696qdd-nixos-system-nixos-holochain-workshop-26.05.20260925.f5c082a.drv

$ nix build .#nixosConfigurations.sensorica-holoport-01.config.system.build.toplevel --print-out-paths
/nix/store/hp7fnqzsiym5ah8nx4wmfb3b50bpnlya-nixos-system-sensorica-holoport-01-26.05.20260925.f5c082a

$ mdbook build
INFO HTML book written to `book`

The switch commands were run against a scratch clone set up like a lab Holoport: lab/holoport-session at c9d2485 with an operator key committed on top. Afterwards git status -sb printed ## main...origin/main [ahead 1], git log --oneline origin/main..main printed only the operator key commit, and the key was still in hosts/common.nix. They were not run on a real Holoport.

VM tests built

Only files under examples/ changed. The root flake's checks.x86_64-linux drvPaths are identical to main at 666c5ae for all 28 checks except moss-dashboard, which reads the source tree and was built locally (passed).

All 14 VM tests were built locally on KVM in one nix build --keep-going (exit 0, 14 vm-test-run-* outputs), vmTestGrafana included with no retry:

• vmTest: passed
• vmTest-0_6: passed
• vmTestBootstrap: passed
• vmTestConductorMetrics-0_6: passed
• vmTestGateway: passed
• vmTestGrafana: passed
• vmTestHoloportInstall: passed
• vmTestMossNode: passed
• vmTestServices: passed
• vmTestServices-noBootstrap: passed
• vmTestWdocker: passed
• vmTestWindtunnel: passed
• vmTestWithHapp: passed
• vmTestWithHapp-0_6: passed

Option reference

• No option was added, changed or removed.
• Options changed, and docs/module-options.md was regenerated with cp "$(nix build .#options-doc --print-out-paths)" docs/module-options.md in the same commit.

Documentation

• docs/ (and README.md, if it says anything about this) updated in this PR, or nothing there describes the changed behaviour.