feat(status): reorder by data flow, sharpen reception signals (#93)

* feat(status): reorder by data flow, sharpen reception signals

Status output now follows the actual data path. Adds a receiver-activity byte sample, narrows the uplink check to ADS-B ports, raises server-reception tiers to match the 5-min sync, folds MLAT privacy in, and bumps --json to v2.

* fix(status): tighten uplink + activity skips, keep forward-compat warn

ADS-B uplink now parses the peer column only so a local listener on :30004/:64004 can't false-positive; netstat fallback enforces ESTABLISHED. Receiver activity skips on warn (not just fail) so malformed INPUT doesn't show a misleading second 'no data' line. Unknown mlat_private values surface as their own warn instead of being silently swallowed by the MLAT-line privacy fold.

* test(status): hide system ss from command -v in netstat branch tests

CI runners ship /usr/bin/ss, so rm'ing the STUB_DIR/ss stub left command -v ss finding the system binary and the ss branch ran instead of the netstat fallback. Override command() in the test scope so BATS run inherits a definition that returns 1 for ss only.

* fix(status): drop internal claim-version from human Website claim line

The (vN) suffix is internal bookkeeping; operators have no actionable use for it and v1 just looks confusing on a freshly-registered feeder. Kept in --json (.claim.version) and the local mirror file for tooling.

Author: d4rken

README.md

@@ -33,14 +33,16 @@ Example:
 ```
 airplanes.live feed check
 
-OK    Feed service         running
-OK    MLAT service         running
 OK    Receiver input       connected at 127.0.0.1:30005
-OK    Airplanes.live link  connected
+OK    Receiver activity    data flowing (256b in 2s sample)
+OK    Feed service         running
+OK    ADS-B uplink         connected
 OK    Feeder ID            11111111-2222-3333-4444-555555555555
 OK    Claim secret         present
-OK    Website claim        registered, not yet claimed (v1)
-OK    Website feed         last data seen 1m ago
+OK    Website claim        registered, not yet claimed
+OK    Server reception     currently receiving (last data seen 1m ago)
+OK    MLAT service         running (name: public)
+OK    Diagnostics push     enabled (default), last push 4m ago
 
 Result: feeding looks healthy
 ```