fix: do not warn on valid known experiments (#18514)

Fixes https://github.com/coder/coder/issues/18024

* drive-by: renames `handleExperimentsSafe` to
`handleExperimentsAvailable` to better match semantics
* defines list of `codersdk.ExperimentsKnown` and updates
`ReadExperiments` to log on invalid experiments
* typescript-ignores `codersdk.Experiments` so apitypings generates a
valid enum list of possible values of experiment
* updates OverviewPageView to distinguish between known 'hidden'
experiments and unknown 'invalid' experiments

codersdk/deployment.go

@@ -3372,6 +3372,18 @@ const (
 	ExperimentAITasks            Experiment = "ai-tasks"             // Enables the new AI tasks feature.
 )
 
+// ExperimentsKnown should include all experiments defined above.
+var ExperimentsKnown = Experiments{
+	ExperimentExample,
+	ExperimentAutoFillParameters,
+	ExperimentNotifications,
+	ExperimentWorkspaceUsage,
+	ExperimentWebPush,
+	ExperimentWorkspacePrebuilds,
+	ExperimentAgenticChat,
+	ExperimentAITasks,
+}
+
 // ExperimentsSafe should include all experiments that are safe for
 // users to opt-in to via --experimental='*'.
 // Experiments that are not ready for consumption by all users should
@@ -3384,6 +3396,9 @@ var ExperimentsSafe = Experiments{
 // Multiple experiments may be enabled at the same time.
 // Experiments are not safe for production use, and are not guaranteed to
 // be backwards compatible. They may be removed or renamed at any time.
+// The below typescript-ignore annotation allows our typescript generator
+// to generate an enum list, which is used in the frontend.
+// @typescript-ignore Experiments
 type Experiments []Experiment
 
 // Returns a list of experiments that are enabled for the deployment.