Ship the 0.8.0 first-hour and campaign milestone

Add the campaign shell, pause-safe checkpoint resume, post-shift campaign
continue, confirmed campaign reset, difficulty presets, searchable Help,
content-matrix validation, recovery events, contextual dialogue, policy/debrief
context and eligible-event previews. Extend persistence with atomic separate
files and add campaign/checkpoint/tutorial smokes. Headless 247/247, Python
94/94, tutorial/campaign/session/scenario smokes green.

src/core/event_scheduler.gd

@@ -11,6 +11,9 @@ signal event_ready(event_data: Dictionary)
 var rng := RandomNumberGenerator.new()
 var _scenario: VenueScenario = null
 var _weighted_pool: Array[Dictionary] = []
+## Difficulty/pacing knob: <1 is calmer, >1 sends more events and routine traffic.
+var spawn_rate_multiplier := 1.0
+var _recent_scripted: Array[String] = []
 
 func _init() -> void:
 	pass
@@ -38,17 +41,47 @@ func pull_due(elapsed_s: float, phase: int) -> Array[Dictionary]:
 			continue
 		var prob: float = event.get("probability", 0.0)
 		var base: float = event.get("base_weight", 1.0)
+		var event_id := str(event.get("id", ""))
+		if str(event.get("kind", "routine")) == "scripted" and event_id in _recent_scripted:
+			continue
 		var spawn_rate: float = event.get("spawn_rate", 0.0)
+		var due_event := false
 		if spawn_rate > 0.0:
 			# Rate-based spawning: emit at most one per second window.
-			if rng.randf() < spawn_rate:
+			if rng.randf() < clampf(spawn_rate * spawn_rate_multiplier, 0.0, 1.0):
 				if rng.randf() < prob:
-					due.append(event.duplicate())
+					due_event = true
 		else:
-			if rng.randf() < prob * base:
-				due.append(event.duplicate())
+			if rng.randf() < clampf(prob * base * spawn_rate_multiplier, 0.0, 1.0):
+				due_event = true
+		if due_event:
+			due.append(event.duplicate())
+			if str(event.get("kind", "routine")) == "scripted" and event_id != "":
+				_recent_scripted.append(event_id)
+				if _recent_scripted.size() > 4:
+					_recent_scripted.pop_front()
 	return due
 
+## Debug/content preview: events that could be selected now, without consuming
+## RNG or marking anything as recently played.
+func preview(elapsed_s: float, phase: int) -> Array[String]:
+	var out: Array[String] = []
+	if _scenario == null:
+		return out
+	for event in _weighted_pool:
+		var time_range: Vector2 = event.get("time_range_s", Vector2(0, _scenario.shift_duration_s))
+		if elapsed_s < time_range.x or elapsed_s > time_range.y:
+			continue
+		if int(event.get("phase", -1)) != phase:
+			continue
+		var event_id := str(event.get("id", ""))
+		if str(event.get("kind", "routine")) == "scripted" and event_id in _recent_scripted:
+			continue
+		out.append("%s (%s)" % [event_id, str(event.get("kind", "routine"))])
+		if out.size() >= 8:
+			break
+	return out
+
 func fallback_routine_traffic(phase: int) -> Array[Dictionary]:
 	## Cheap routine traffic so the street never feels empty.
 	var out: Array[Dictionary] = []
@@ -56,10 +89,19 @@ func fallback_routine_traffic(phase: int) -> Array[Dictionary]:
 	if pool.is_empty():
 		return out
 	for i in 3:
-		if rng.randf() < 0.35:
+		if rng.randf() < clampf(0.35 * spawn_rate_multiplier, 0.0, 1.0):
 			out.append(pool[rng.randi_range(0, pool.size() - 1)].duplicate())
 	return out
 
+func snapshot() -> Dictionary:
+	return {"rng_state": rng.state, "recent_scripted": _recent_scripted.duplicate()}
+
+func restore(data: Dictionary) -> void:
+	rng.state = int(data.get("rng_state", rng.state))
+	_recent_scripted.clear()
+	for event_id in data.get("recent_scripted", []):
+		_recent_scripted.append(str(event_id))
+
 func _routine_pool(phase: int) -> Array:
 	var out: Array = []
 	for event in _weighted_pool: