Add Alert node for out-of-game notifications

[Gaetarra]

What This Changes

Adds an ALERT node so a graph can reach someone who is not looking at the
screen. Automation runs while the player is tabbed out or AFK, and MESSAGE
only reaches chat, which nobody sees while a farm runs unattended.

Two modes:

• Play Sound — any vanilla sound id plus a volume, played through the sound
  manager with SimpleSoundInstance.forUI so the alert is not attenuated by
  where the player is standing.
• Send Webhook — POSTs the node's text to an https endpoint set in
  settings. This is the mode that reaches a phone.

Verification

Check	Status
./gradlew :common:test -Pmc_version=1.21.11	Not run locally. Relying on CI.
verifyCompatibilityManifest verifyCompatibilityStructure verifyBuildGenerationRouting	Not run locally. Relying on CI.
Compiles on 1.21 / 1.21.8 / 1.21.10 / 1.21.11	Not run locally. All new code is version-agnostic common/src/main, but that is an argument, not a check.
Compiles on 26.1 / 26.2 (-p mc26, both loaders)	Fabric passes on both. NeoForge passes on 26.1.2. NeoForge on 26.2 fails with Could not find net.neoforged:neoforge:unsupported — the manifest lists neoforge=unsupported for 26.2 and the mc26 build reads it without the root build's takeUnless filter. Pre-existing, unrelated to this change.
Clicked through the affected UI in a dev client	Yes — mode selector opens, Sound and Volume are editable, both modes render as English.

Notes For Review

Non-obvious decisions:

• The node completes its future as soon as the notification is dispatched,
  rather than awaiting the HTTP response. An alert must never stall the graph it
  is reporting on, so webhook failures are logged instead of propagated.
• Webhook sends are rate limited to one per three seconds. An Alert inside
  Forever would otherwise hammer the endpoint, and Discord kills webhooks that
  are hammered.
• Payload shape is chosen by host — Discord needs a JSON body, ntfy takes
  raw text. A deliberate two-case heuristic rather than a third node mode; there
  is a comment marking it as the thing to revisit if a third shape shows up.
• The URL is validated once, in SettingsManager.sanitizeWebhookUrl, and
  https is required. It is a user-supplied string driving an outbound request
  from the game client, so it is checked at the boundary rather than at each
  call site. NodeAlertTest covers the rejection cases.
• Alert reuses the multi-line text fields that MESSAGE and CALCULATE
  already have, by joining NodeTextContent, so message text supports runtime
  variable interpolation with no new UI.
• Toast was considered and left out. It only helps someone already watching
  the screen, which is not the case this node exists for.

Out of scope, deliberately:

• The webhook URL has no settings-popup field yet, so it is set by editing
  pathmind/settings.json. That control lives in a Stonecutter source file with
  15 conditional regions; adding it here would have made this much harder to
  review. Happy to follow up.

Worth a look by hand: NodeCatalog gained NodeType.ALERT in the
RENDER_INLINE_PARAMETERS tag. Without it NodeGraph.rendersInlineParameters
is false, the parameter strip is never drawn, and the mode selector that lives
inside that strip is unreachable. That is a general trap — several existing
node types have modes with no way to select them — but this PR only fixes it
for ALERT.