[SER-2815] Expose the remote-URL downloader settings

[0mar-K]

Companion to https://linear.app/nutrient/issue/SER-2815 and the Document Engine PR.

Summary

Document Engine 1.19.0 makes its remote-URL downloader configurable. The reference architecture points customers at this chart, so without these values the feature is unreachable for anyone deploying that way.

Defaults match what Document Engine used while these were hardcoded, so an existing deployment is unaffected.

On hold until Document Engine 1.19.0 is out. Tracked as a release TODO in the monorepo.

Two things for whoever merges this. The 1.19.0 release lands as its own commit that bumps appVersion and takes the next chart minor, which by the pattern of 1.16.0 to 8.4.0, 1.17.0 to 8.5.0 and 1.18.0 to 8.6.0 will be 8.7.0. So this PR needs renumbering to 8.8.0 once that lands. And the changelog entry deliberately carries no "requires 1.19.0" note, because merging after the appVersion bump makes it true by ordering and the chart has never version-gated an entry.

Fix

• values.yaml - config.urlFetchPoolSize, config.urlFetchQueueTimeoutSeconds, config.urlFetchQueueMaxSize, next to the existing urlFetchTimeoutSeconds
• templates/configmap.yaml - maps them, seconds to milliseconds like its neighbours
• Chart.yaml - 8.6.3 to 8.7.0, backward compatible addition
• CHANGELOG.md, README.md (helm-docs), values.schema.json (helm schema)

QA

• helm template with --set config.urlFetchPoolSize=32 renders DOWNLOADER_WORKER_POOL_SIZE: "32", and 5 seconds renders DOWNLOADER_BROKER_CLIENT_QUEUE_TIMEOUT: "5000"
• --set config.urlFetchPoolSize=0 is rejected by the schema, matching the validation in Document Engine
• helm lint passes

[zrzka]

Note: values.schema.json was hand-edited to mirror the existing workerPoolSize and urlFetchTimeoutSeconds entries, because the helm schema plugin is not installed here. Worth regenerating if you have it.

This is clearly coming from an agent, which is fine, but it also shows that you don't have all the tools required installed. Install them and generate the schema, do not hand edit. Any subsequent generation can produce more changes, make following PRs unnecessary big.

We should also put this PR on hold, add a TODO item here, and merge when DE 1.19 is out (unless we want to have this option available in nightly).

[0mar-K]

Holy! Yea, I didn't know about this at all. First time to touch such changes. Tried to weigh it right with the agent but apparently failied 😅 Many thanks for the correction, @zrzka

All three done. Schema is generated, PR back to draft, TODO is on #58563

Waiting for 1.19 rather than nightly. I set both variables on released 1.18.1 and nothing changed, still 16 and shedding at 5s, so merging early would just hand people a dead knob. Is that the right way?

Also put up #168 for your review. It's for the regeneration command part.