fix consumer CLI queries, localnet tooling, and consumer export

[giunatale]

Unbreaks the local development loop and a handful of CLI paper cuts.

What

• consumer-fee-pool-claims pagination: the --page-key flag was read without
  decoding, so paging past page 1 failed; it now uses the page-key-decoded
  flag-set like the sibling paginated commands.
• New consumer-liveness CLI query command — the gRPC query existed but was
  unreachable from the CLI; every provider query is now exposed. The liveness
  operator guide documents the command and its REST form.
• create-consumer/update-consumer help and the localnet payload used a
  nonexistent field name (ccv_timeout_period), a timeout above the 24h
  protocol cap, and lacked the required safe_mode_threshold — so
  make localnet-start could not create a consumer at all. Both fixed.
• ts-relayer localnet networking on macOS: --network host is Linux-only, so
  the relayer container could not reach the host chains. It now dials
  host.docker.internal (with --add-host=...:host-gateway so Linux keeps
  working), both chains bind RPC to 0.0.0.0, and the relayer account is
  funded on the provider from genesis (previously it could not pay for
  provider-side client creation — a second bug the networking failure masked).
• consumer export no longer fails on a consumer that has not yet received a
  validator set: it exports an empty set (with a unit test), instead of
  erroring.
• The e2e harness hid the reason a container command failed. dockerExec's
  StartExec reports whether the exec succeeded, not how the command inside
  it exited, so a command that failed came back with a nil error and empty
  stdout. Callers unmarshal that stdout, so the test failed on the empty
  document -- failed to decode <x> response: with nothing after the colon --
  while the actual message sat on a discarded stderr. It now inspects the exit
  code and logs the code, the command, stdout and stderr when it is non-zero.
  The returned error stays nil deliberately: several callers run commands they
  expect to fail and assert on stderr themselves.

Testing

make localnet-start verified end to end on macOS (relayer up, IBC clients on
both sides, client-established + validator-set sync). Build, lint, unit, and
the new app-level export test are green. Both Docker e2e suites pass; the
dockerExec change is diagnostics only and alters no assertion.

[giunatale]

Branched from giunatale/feat/offline-detection (#63).
Opened against that branch so only this PR's commit shows; will retarget to main after #63 lands and this rebases.

[julienrbrt]

lgtm!