feat: usage report transaction IDs, usage history and exports

[fuzcap]

What does this PR change?

CLI support for two Kaiten features: idempotent usage reports (transactionId) and the usage history. Server: kaitencloud/kaiten#16. SDK: kaitencloud/sdk-go#1.

• kaiten instances usage report … --transaction-id <id>. Kaiten applies a keyed report at most once, so the SDK retries it on network errors and 500/502/503/504, and running the command again is safe. A replayed report ("already counted") and dropped metadata (above 4 KiB) are noted on stderr; stdout stays the usage document scripts read. The flag overrides a key given in --file/--payload.
• Exit codes. A malformed key exits 2 before any request. A key already used for a different report is a 409 and exits 5, like any rejection: a correction is a new report under a new key.
• kaiten instances usage history <instance> <entitlement>. The accepted reports in order, with the counter before and after each one, the delta, the limit and the key. Flags: --from, --to (last 30 days by default), --transaction-id, --limit.
• kaiten instances usage export [<instance> <entitlement>]. CSV (default) or NDJSON, streamed to stdout or --output-file:
  • with the two arguments, one pair, up to 366 days per run;
  • without them, the whole organization, up to 31 days per run, narrowed by --instance, --instance-id, --entitlement and --entitlement-id. The ID filters reach deleted instances and entitlements.
  • Exports run on a client with no overall timeout (the server must still start answering within 15 s) and outside the command's 15 s deadline; Ctrl-C still cancels. A file is written as <name>.partial and renamed when complete.
• github.com/kaitencloud/sdk-go is pinned to a pseudo-version of feat: usage report transaction IDs and the usage history sdk-go#1's branch. Before merging: merge and tag that PR, then bump the pin to the tag.

Why?

A report that timed out could not be retried safely: it might count twice. A key makes the retry safe, and the CLI is how operators and scripts send one-off reports. The history commands let them see, and keep, what was counted.

Testing

task test      # ok, also with -race
task lint      # 0 issues
task deadcode  # nothing unreachable

Against a fake API:

• Report: the key goes into the body, and no key is sent without the flag. A replay is noted on stderr with stdout still a JSON document. A malformed key exits 2 with no request; a reused key exits 5.
• History: the request path and from query, and the table's columns (key, limit, negative delta).
• Export:
  • a pair streams to stdout byte for byte;
  • the organization export goes to a file with its filters in the query, leaving no .partial behind;
  • invocation mistakes exit 2 and send nothing: one argument, three arguments, organization filters with a pair, an unknown format, an unparsable --from;
  • a 422 OutsideRetention exits 5 and creates no file.

Checklist

• I have read CONTRIBUTING.md.
• Every commit in this PR includes a valid DCO Signed-off-by line.
• I have the right to submit all material in this PR.
• I have not included secrets or confidential data.
• I have updated tests where appropriate.
• I have updated documentation where appropriate.
• I have preserved required third-party licenses and attributions.