fix(cli): announce truncated structured list pages on stderr

[ysyneu]

What

In json/toon mode, PrintList suppresses the "Showing N results (page P, total T)." footer to keep stdout byte-pure for jq/toon pipelines. That left a gap: a page short of the server-reported total (e.g. the default --limit 20 of a far larger total) looked exactly like the whole set to anything reading stdout.

PrintList now prints a note: showing N of T total results (page P); raise --limit or use --page for the rest line on stderr when the page doesn't cover the total — same pattern as the existing projection notes. Table mode is unchanged (it keeps the stdout footer); a page that covers the total prints nothing extra. This covers every paged list command that goes through PrintList (alert list, alert-event list, incident list, change list, audit search, insight incident-list).

Overflow hard-failure is now pinned by tests

A compact list projection that can't fit its 16 KiB budget already fails the command (the error propagates out of RunE → main exits 1 with Error: projected list is … on stderr and nothing on stdout). That behavior had no command- or binary-level coverage, so this adds:

• TestCommandListProjectionOverflowFails (incident list + alert-event list): irreducible projection → Execute returns the byte-limit refusal and stdout stays empty.
• TestProjectionOverflowFailsHard (built binary against a stub server): non-zero exit code, empty stdout, refusal on stderr — so a pipeline reading stdout sees a failed call, never an empty page masquerading as "no data".
• TestCommandAlertListStructuredAnnouncesTruncation: the new stderr note fires on a truncated structured page, stays silent when the page covers the total, and table mode keeps its stdout footer.

Verification

• make check (gofmt/gci, golangci-lint, go test -race ./..., build): all green.
• End-to-end with the built binary against a stub server: structured truncated page → exit 0, parseable stdout, note on stderr; table mode → stdout footer, no stderr note; over-budget projection → exit 1, empty stdout, Error: projected list is … exceeds the 16384-byte limit on stderr.