isOnboardingInputAllowed fails on mixed-case or untrimmed demo and input kinds

[hsusul]

Describe the bug

In src/helpers/onboardingInputPolicy.js:

isOnboardingInputAllowed(onboardingActive, demoKind, inputKind) performs strict case-sensitive checks against ONBOARDING_DEMO_KINDS and demoKind === inputKind. When demoKind or inputKind is passed with mixed casing (e.g. "Dictation", "Assistant") or surrounding whitespace, it returns false during active onboarding demos instead of allowing the corresponding input.

To Reproduce

1. Call isOnboardingInputAllowed(true, "Dictation", "dictation") -> returns false (expected true).
2. Call isOnboardingInputAllowed(true, " Assistant ", "assistant") -> returns false (expected true).

Expected Behavior

isOnboardingInputAllowed should normalize demoKind and inputKind case-insensitively with whitespace trimming.

[Chadpiha]

Closing together with #1832 — full reasoning over there. Thanks for the report, @hsusul!