Add interactive pagination for JSON list output

[simonfaltum]

Why

List commands without a row template fall through to the JSON renderer, which today dumps the entire array in one go. For workspaces with hundreds of apps, jobs, pipelines, or files, the output scrolls past before you can read any of it. An interactive terminal should get a chance to step through the output.

This PR adds that pager for the JSON case. A follow-up (#5015) adds the same interaction for commands that do have a row template, reusing the shared infrastructure introduced here.

Changes

Before: RenderIterator always emitted the entire JSON array at once.

Now: when stdin, stdout, and stderr are all TTYs and the command has no row template, databricks <resource> list streams 50 JSON items at a time and prompts on stderr:

[space] more  [enter] all  [q|esc] quit

SPACE fetches and renders the next page. ENTER drains the remaining iterator (still interruptible by q/esc/Ctrl+C between pages). q/esc/Ctrl+C stop immediately. The emitted JSON is always a syntactically valid array — even on early quit — so anything that redirects stdout still gets parseable output.

Piped output and redirected stdout keep the existing non-paged behavior: the capability check requires all three streams to be TTYs.

New files under libs/cmdio/:

• capabilities.go — SupportsPager() (stdin + stdout + stderr all TTYs, not Git Bash).
• pager.go — shared plumbing: raw-mode stdin setup with a key-reader goroutine, pagerNextKey / pagerShouldQuit, a crlfWriter to compensate for the terminal's cleared OPOST flag while raw mode is active, and the prompt/key constants.
• paged_json.go — the JSON pager itself. Defers writing the opening [ until the first item is encoded, so empty iterators and iterators that error before yielding produce valid [].
• render.go — RenderIterator routes to the JSON pager when the capability check passes and no row template is set.

No cmd/ changes. No new public API beyond Capabilities.SupportsPager.

Test plan

• go test ./libs/cmdio/... (all passing, new coverage includes crlfWriter, the key helpers, and every pager control path for JSON output).
• make checks passes.
• make lintfull passes (0 issues).
• Manual smoke in a TTY against a command that renders as JSON — space fetches pages, enter drains, q/esc/Ctrl+C quit, the on-screen JSON remains valid after any of these.
• Manual smoke with piped stdout (| jq) — output matches main.

[github-actions]

Approval status: pending

/libs/cmdio/ - needs approval

6 files changed
Suggested: @mihaimitrea-db
Also eligible: @tanmay-db, @renaudhartert-db, @hectorcast-db, @parthban-db, @Divyansh-db, @tejaskochar-db, @chrisst, @rauchy

General files (require maintainer)

Files: NEXT_CHANGELOG.md, NOTICE, go.mod
Based on git history:

• @pietern -- recent work in libs/cmdio/, ./

_{Any maintainer (@andrewnester, @anton-107, @denik, @pietern, @shreyas-goenka, @renaudhartert-db) can approve all areas.
See OWNERS for ownership rules.}