API key NA guard not applied to embedding provider check

[seanthimons]

Source: PR #278 review (round 1)
Severity: LOW
File: R/mod_search_notebook.R:2875

The embedding guard still uses nchar(provider_or$api_key) == 0 without an is.na() guard. nchar(NA) returns NA which causes a warning. The same is.na() || !nzchar() fix from mod_query_builder.R:82 should be applied here for consistency.

Suggested fix: Change to is.null(provider_or$api_key) || is.na(provider_or$api_key) || !nzchar(provider_or$api_key).

[seanthimons]

Fixed in 248a55b — API key guard now handles NA via is.na() + nzchar()