Goal 3 SP7: Integration tests and false-positive validation

[bedaHovorka]

Goal 3 SP7: integration tests and false-positive validation for collision detection.

Parent: #610

Deliverables

New files:

• core/src/jvmTest/kotlin/cz/vutbr/fit/interlockSim/sim/collision/CollisionDetectionIntegrationTest.kt
• core/src/jvmTest/kotlin/cz/vutbr/fit/interlockSim/sim/collision/PredictiveTtcTest.kt
• core/src/jvmTest/kotlin/cz/vutbr/fit/interlockSim/sim/collision/AutoPauseHaltTest.kt
• docs/MANUAL_TEST_PLAN_GOAL_3.md

Tests

1. Reservation conflict integration — two trains request same entry-exit path; exactly one ReservationConflict emitted; no deadlock.
2. Block-entry violation integration — deliberately bypass reservation and drive a second train into an occupied block; warning emitted.
3. Predictive TTC false-positive suite — run 100 iterations of safe multi-train scenarios and assert zero PredictiveCollision warnings.
4. Auto-pause/halt integration — @RepeatedTest(50) verifying pause/halt behavior.

Acceptance criteria

• All new tests pass.
• No existing Goal 1/2 tests regress.
• False-positive rate for predictive TTC is documented (target < 1% in safe scenarios).

Quality gate

./gradlew clean build detekt ktlintCheck :core:test :core:integrationTest :desktop-ui:test

Depends on

#615 Goal 3 SP5, #616 Goal 3 SP6

Downstream link

Goal 9 SP7 (#593) end-to-end integration will extend this false-positive validation suite.

[bedaHovorka]

Follow-up from code review of PR #694 (Goal 3 SP5, auto-pause/auto-halt):

Train.requestHalt() — the one new production method in SP5 — currently has zero test coverage, direct or indirect. Its doc comment claims it is safe/idempotent to call even if the train has already stopped, and is designed to be invoked re-entrantly from inside DynamicTrackBlock.enter()'s emit-before-throw path (i.e., while the same train's movement coroutine is still on the call stack, immediately before the IllegalStateException for double-occupancy unwinds). That specific interaction is untested anywhere.

Please make sure the SP7 integration suite (AutoPauseHaltTest.kt per the deliverables above) includes:

1. A real single-train scenario wiring registerHaltCallback(train.name, train::requestHalt) on a DefaultSimulationContext (following the BlockEntryViolationWarningTest fixture pattern) that asserts the train's velocity is actually zero after a double-occupancy BlockEntryViolation fires the halt callback mid-enter().
2. A direct idempotency check — calling requestHalt() twice (or on an already-stopped train) — to confirm it doesn't throw or misbehave.

(Also noted: registerHaltCallback/autoHaltTrainOnViolation aren't wired into any production loop yet — MultiTrainLoop/ShuntingLoop/GUI all have zero references. Not blocking this issue, just flagging in case it affects the integration test's setup.)