fix: merge readiness — display_enabled config, real pubkey, probe interval, dedup services

- Add display_enabled config field (default true, parsed from config.json)
- Guard display_init/display_update behind display_enabled check
- Fix discovery pubkey: replace hardcoded all-zeros with identity_get()->npub_hex
- Revert MINT_HEALTH_PROBE_INTERVAL_S from 30 (testing) to 300 (production)
- Remove duplicate services_start_task call in IP event handler
- Fix UTF-8 arrow in STA auth threshold log message
- Gitignore compiled test binaries (test_mcp_handler, test_mint_health, etc.)
- Remove tracked test binaries from git

Verified on Board B (stable):
- make test-discovery-b: pubkey=d6bfe100..., metric=milliseconds, price_per_step tags
- make test-mints-b: 4 mints listed with reachable field
- Wallet: 40 sats balance with 4 proofs from previous payment
- All API endpoints responding (discovery, mints, wallet, whoami, portal)
- 75/75 unit tests passing

1 files changed, 7 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index b2f1400..80cd5ed 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,4 +19,11 @@ tests/unit/test_identity
 tests/unit/test_nostr_event
 tests/unit/test_cashu
 tests/unit/test_session
+tests/unit/test_mcp_handler
+tests/unit/test_mint_health
+tests/unit/test_tollgate_client
+tests/unit/test_cvm_server
+tests/unit/test_lnurl_pay
+tests/unit/test_lightning_payout
+tests/unit/test_nip04
 interop/routers.env