fix: log actual providers cache path instead of function reference

[Ajithkumar003-dev]

What

In UpdateProviders, the slog.Info call was passing cachePathFor (the function itself) as the "to" log attribute instead of invoking it with "providers" to get the resolved path string.

`go
// Before
slog.Info("Providers updated successfully", "count", len(providers), "from", pathOrURL, "to", cachePathFor)

// After
slog.Info("Providers updated successfully", "count", len(providers), "from", pathOrURL, "to", cachePathFor("providers"))
`

Why it matters

This caused the structured log line to record the function pointer address (e.g. 0x6c3f40) as the to field instead of the actual file path, making it impossible to tell from logs where providers were written to disk.

Compare with UpdateHyper 33 lines below, which already calls cachePathFor("hyper") correctly. This commit applies the same pattern to UpdateProviders.

Testing

Run crush update-providers and check that the log line now shows the full cache file path under the to key.

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