test(acceptance): implement IO-3, IO-4, and IO-7..IO-11 onboarding tests

Adds comprehensive installation and onboarding test coverage:

IO-3: Single node end-to-end onboarding
- Fresh install -> token provisioning -> spaxel-sim --nodes 1
- Verifies discovered->online transition within 10s
- Tests label/position persistence across restart

IO-4: Multi-node fleet bring-up
- Validates 6 nodes all reach online simultaneously
- Checks non-overlapping TX slot assignment
- Verifies GDOP/coverage computation and telemetry flow

IO-7: Provisioning timeout handling
- Node goes silent after connecting
- Verifies stale/offline marking within heartbeat window
- Confirms no mothership crash

IO-8: Bad/expired token rejection
- Tests clear error response for invalid tokens
- Ensures no zombie rows created

IO-9: Duplicate MAC handling
- Two nodes with same MAC scenario
- Verifies deduplication or rejection

IO-10: Mid-onboarding interruption
- Simulator killed during onboarding
- Confirms node can reconnect without stale locks

IO-11: Firmware version skew
- Old firmware version flagged for OTA
- Onboarding completes without losing node

Closes: bf-2hi0h

mothership/test/acceptance/integration_test.go

@@ -47,6 +47,14 @@ func TestMain(m *testing.M) {
 		{"IO1_FreshInstall_FirstBoot", IO1_FreshInstall_FirstBoot},
 		{"IO2_IdempotentRestart", IO2_IdempotentRestart},
 		{"IO2_UpgradeInPlace", IO2_UpgradeInPlace},
+		{"IO3_SingleNodeOnboarding", IO3_SingleNodeOnboarding},
+		{"IO4_MultiNodeFleetBringUp", IO4_MultiNodeFleetBringUp},
+		{"IO6_FullNewUserE2E", IO6_FullNewUserE2E},
+		{"IO7_ProvisioningTimeout", IO7_ProvisioningTimeout},
+		{"IO8_BadExpiredToken", IO8_BadExpiredToken},
+		{"IO9_DuplicateMAC", IO9_DuplicateMAC},
+		{"IO10_DropMidOnboard", IO10_DropMidOnboard},
+		{"IO11_FirmwareVersionSkew", IO11_FirmwareVersionSkew},
 		{"AS1_FirstTimeSetup", AS1_FirstTimeSetupIntegration},
 		{"AS2_WalkingDetection", AS2_WalkingDetectionIntegration},
 		{"AS3_FallDetection", AS3_FallDetectionIntegration},