Move ai settings to a config

[aquaticcalf]

from .env.example

# ── AI assistant (disabled by default) ───────────────────────────────────────
# Set to "true" to enable the Ask AI widget in the top bar.
# The widget is rendered even when disabled; it shows an informational notice.
NEXT_PUBLIC_DOCS_AI_ENABLED=false

# The following vars only matter when NEXT_PUBLIC_DOCS_AI_ENABLED=true.
# They are read by the /api/ask route at runtime (server-only, never sent to
# the browser).
# DOCS_AI_PROVIDER=anthropic
# DOCS_AI_MODEL=claude-haiku-4-5
# ANTHROPIC_API_KEY=

other than the api key, everything else makes more sense to me as a config file setting

we can have autocomplete and typesafety that way

also, why not make it a generic AI_API_KEY or something?

that way, i dont need to change env var name while changing providers

[CharanMN7]

You're right, that's how it should be. I didn't get that far with this, to try out the AI features in a production example because we haven't defined anything around how to protect AI access on a docs page yet. So, right now it's just dangling over there for anyone to figure out, modify and use it if they care enough (in other words, carelessly implemented and/or left incomplete).

We shall get to this once the authentication/security scenario is documented.