Exit and serve static html message on SystemCore

[samfreund]

Description

Needs to be tested on SC.

Running on SystemCore is bad, as PV tends to be a resource hog. Additionally, if issues arise, it can cause major problems. We want to ensure that a team has to intentionally take actions in order to run PV on SC, thus we serve a static webpage informing teams that SC isn't supported and exit.

Meta

Merge checklist:

• Pull Request title is short, imperative summary of proposed changes
• The description documents the what and why
• If this PR changes behavior or adds a feature, user documentation is updated
• If this PR touches photon-serde, all messages have been regenerated and hashes have not changed unexpectedly
• If this PR touches configuration, this is backwards compatible with settings back to v2025.3.2
• If this PR touches pipeline settings or anything related to data exchange, the frontend typing is updated
• If this PR addresses a bug, a regression test for it is added

[mcm001]

• you never call javelin.serve
• you must let javalin live to be a web server. You can't exit...

[samfreund]

you never call javelin.serve

app = io.javalin.Javalin.create(cfg -> cfg.showJavalinBanner = false).start(port);

This is functionally equivalent, it does the same thing and serves it.

you must let javalin live to be a web server. You can't exit...

We suspend the process, the exit is only there if something in the webserver fails.

[samfreund]

[2025-10-31 19:37:30] [General - Main] [INFO] Starting PhotonVision version dev-v2025.3.2-48-g9519bbae on platform Linux x64
[2025-10-31 19:37:30] [General - Main] [ERROR] SystemCore is not a supported platform for PhotonVision!
Please visit https://docs.photonvision.org/en/latest/docs/quick-start/common-setups.html#systemcore-support for more information.
[main] INFO io.javalin.Javalin - Starting Javalin ...
[main] INFO org.eclipse.jetty.server.Server - jetty-11.0.15; built: 2023-04-11T18:37:53.775Z; git: 5bc5e562c8d05c5862505aebe5cf83a61bdbcb96; jvm 17.0.16+8-Ubuntu-0ubuntu122.04.1
[main] INFO org.eclipse.jetty.server.session.DefaultSessionIdManager - Session workerName=node0
[main] INFO org.eclipse.jetty.server.handler.ContextHandler - Started i.j.j.@1afd44cb{/,null,AVAILABLE}
[main] INFO org.eclipse.jetty.server.AbstractConnector - Started ServerConnector@2f8f5f62{HTTP/1.1, (http/1.1)}{0.0.0.0:5800}
[main] INFO org.eclipse.jetty.server.Server - Started Server@2bbaf4f0{STARTING}[11.0.15,sto=0] @193ms
[main] INFO io.javalin.Javalin - Listening on http://localhost:5800/
[main] INFO io.javalin.Javalin - You are running Javalin 5.6.2 (released July 31, 2023. Your Javalin version is 823 days old. Consider checking for a newer version.).
[main] INFO io.javalin.Javalin - Javalin started in 108ms \o/
[2025-10-31 19:37:30] [General - Main] [INFO] Served SystemCore warning page on port 5800 - process will remain running to serve the page.
^CCommand exited with non-zero status 130
   Command being timed: "java -jar photonvision-dev-v2025.3.2-48-g9519bbae-linuxx64.jar"
   User time (seconds): 0.51
   System time (seconds): 0.07
   Percent of CPU this job got: 2%
   Elapsed (wall clock) time (h:mm:ss or m:ss): 0:21.57
   Average shared text size (kbytes): 0
   Average unshared data size (kbytes): 0
   Average stack size (kbytes): 0
   Average total size (kbytes): 0
   Maximum resident set size (kbytes): 86140
   Average resident set size (kbytes): 0
   Major (requiring I/O) page faults: 0
   Minor (reclaiming a frame) page faults: 18657
   Voluntary context switches: 6507
   Involuntary context switches: 62
   Swaps: 0
   File system inputs: 0
   File system outputs: 72
   Socket messages sent: 0
   Socket messages received: 0
   Signals delivered: 0
   Page size (bytes): 4096
   Exit status: 130

For reference, this is the resources exiting takes on my system.