feat: plane-2 tool-call intent validation (path containment slice)

Implements the full vertical slice for invariant #9 tool-call assessment:
- core:toolintent — new module with ToolCallRule seam, ToolCallAssessor,
  WorldProbe/FileSystemWorldProbe, WorkspacePolicy, PathContainmentRule,
  and RiskMapping (assessment → RiskSummary / AssessedIssue)
- core:tools — ToolCallAssessmentRecord + ToolInvocationRecord.assessment
  field; DefaultToolReducer handles ToolCallAssessedEvent (replay proof)
- core:config — ToolsConfig gains workspaceRoot + privilegedLocations;
  ConfigLoader parses both; DEFAULT_PRIVILEGED_LOCATIONS built-in
- core:kernel — OrchestratorEngines gains toolCallAssessor/workspacePolicy/
  worldProbe fields; SessionOrchestrator.dispatchToolCalls runs
  runPlane2Assessment before the tier gate: BLOCK → hard-reject without
  executing; PROMPT_USER → elevates tier into approval path with plane2Risk
  in the ApprovalRequestedEvent
- apps/server — constructs PathContainmentRule + ToolCallAssessor +
  WorkspacePolicy from config and wires them into OrchestratorEngines

Assessment is recorded as ToolCallAssessedEvent (environment observed once,
facts stored, replay reads events — invariant #9). Assessor and WorldProbe
are only invoked on the live orchestrator path, never in replay.

core/kernel/build.gradle

@@ -16,6 +16,7 @@ dependencies {
     implementation project(':core:artifacts')
     implementation project(':core:artifacts-store')
     implementation project(':core:risk')
+    implementation project(':core:toolintent')
     implementation "org.slf4j:slf4j-api:2.0.16"
 }
 tasks.named("koverVerify").configure { enabled = false }