feat: remove agent workspaces limit (#21998)

In relation to
[`internal#1281`](https://github.com/coder/internal/issues/1281)

Managed agent workspace build limits are now advisory only. Breaching
the limit no longer blocks workspace creation — it only surfaces a
warning.

- Removed hard-limit enforcement in `checkAIBuildUsage` so AI task
builds are always permitted regardless of managed agent count.
- Updated the license warning to remove "Further managed agent builds
will be blocked." verbiage.
- Updated tests to assert builds succeed beyond the limit instead of
failing.
- Removed the "Limit" display from the `ManagedAgentsConsumption`
progress bar — the bar is now relative to the included allowance (soft
limit) only, and turns orange when usage exceeds it.

Bonus:

- De-MUI'd `LicenseBannerView` — replaced Emotion CSS and MUI `Link`
with Tailwind classes.
- Added `highlight-orange` color token to the Tailwind theme.

codersdk/licenses.go

@@ -12,8 +12,9 @@ import (
 )
 
 const (
-	LicenseExpiryClaim                = "license_expires"
-	LicenseTelemetryRequiredErrorText = "License requires telemetry but telemetry is disabled"
+	LicenseExpiryClaim                          = "license_expires"
+	LicenseTelemetryRequiredErrorText           = "License requires telemetry but telemetry is disabled"
+	LicenseManagedAgentLimitExceededWarningText = "You have built more workspaces with managed agents than your license allows."
 )
 
 type AddLicenseRequest struct {