Add structured plugin command events

[gabek]

Plugin command tables now use the accepted chat message path for matching, arguments, moderator gates, and cooldowns.

• Match every registered command declaration, so duplicate commands in different plugins all run.
• Keep unknown, moderator-denied, and cooldown-limited invocations silent.
• Deliver a targeted, reserved chat.command event without adding a plugin permission.
• Keep command messages available to ordinary chat handlers, including !help and !commands.
• Preserve the built-in aggregated help response while allowing plugins to add their own responses.
• Prune expired per-user cooldown entries and reset cooldown state when a plugin reloads.
• Update the wire contract snapshot and rebuild both embedded language engines.

A matching plugin receives this internal payload:

{
  "message": {"id": "m1", "body": "!up one two", "user": {"id": "u1"}},
  "command": "uptime",
  "invokedAs": "up",
  "args": ["one", "two"],
  "argString": "one two"
}

The paired SDK change is owncast/plugin-sdk#3.

Testing included the plugin and pluginhost Go suites, direct matching and cooldown coverage, the host-runtime tests, and the complete JavaScript and Python mod-commands scenarios.

Required checklist

Do not remove this section. These checkboxes are required and validated.

• I have personally tested these changes and verified they work as intended.
• I understand the code I'm submitting and can explain how it works if asked.
• I included a screenshot, logs, example payload to demonstrate the change, or it really doesn't need it.
• This is a frontend change and it supports translations, or it's not a frontend change.
• The code has been run through the proper linters and/or formatters for the language.
• There is an issue discussing this change and it's assigned to me.

[Copilot]

Pull request overview

This PR adds a structured, host-routed plugin command dispatch path so plugin-declared chat commands are matched by the host, gated (mod-only), cooldown-managed per user, and delivered as a reserved chat.command event while preserving existing chat message delivery and the aggregated built-in !help response.

Changes:

• Introduces host-side command matching/dispatch (chat.command) with alias support, moderator gating, and per-user cooldown tracking.
• Extends the plugin wire types to include CommandInfo, CommandEvent, and clientId on HostChatMessage, updating the contract snapshot and related tests.
• Updates pluginhost event flow so accepted chat messages still notify ordinary chat handlers and additionally trigger command dispatch.

Reviewed changes

Copilot reviewed 13 out of 15 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
services/plugins/shared_engine_test.go	Extends shared-engine tests to verify command registration and targeted command dispatch behavior.
services/plugins/plugin-contract.json	Updates the wire contract snapshot with new command/event types and clientId on chat messages.
services/plugins/manifest.go	Removes local CommandInfo and updates manifest commentary to reflect host-side command routing.
services/plugins/manager.go	Adds per-plugin cooldown state fields and clarifies command registration semantics during load.
services/plugins/hostfns.go	Defines CommandInfo, CommandEvent, and adds clientId to HostChatMessage for the plugin wire layer.
services/plugins/help.go	Centralizes default command prefix and !help/!commands alias handling.
services/plugins/events.go	Reserves and documents the new chat.command event type.
services/plugins/dispatcher_test.go	Ensures reserved event type coverage includes chat.command.
services/plugins/contract_test.go	Updates contract test messaging and adds an UPDATE_CONTRACT regeneration path.
services/plugins/commands.go	Implements command matching, gating, cooldown pruning, and targeted chat.command delivery.
services/plugins/commands_test.go	Adds unit tests for matching, duplicate dispatch, moderator gating, and cooldown behavior.
pluginhost/pluginhost.go	Updates help responder comment to reflect continued chat delivery plus command dispatch.
pluginhost/pluginevents.go	Runs command dispatch after notifying chat.message.received subscribers for accepted messages.

[cypress]

Owncast Web Frontend    Run #33264

Run Properties:   Passed #33264  •  03c125ba46: feat(plugins): route declared chat commands

Project	Owncast Web Frontend
Branch Review	gek/plugin-command-events
Run status	Passed #33264
Run duration	05m 45s
Commit	03c125ba46: feat(plugins): route declared chat commands
Committer	Gabe Kangas
View all properties for this run ↗︎

---

Test results
Failures	0
Flaky	0
Pending	0
Skipped	0
Passing	131
View all changes introduced in this branch ↗︎

[gabek]

The Windows Go job has failed twice in the existing TestManager_Install_ReloadsRunningInstanceOnUpdate test with the same .ocpkg rename file-lock error. Ubuntu passes. This change does not touch the install, reload, package-close, rename, or remove paths used by that test, so I am treating it as the existing Windows file-lock flake rather than changing unrelated lifecycle code here.