feat(acr): Store 2 soft-confidence hints + Store 1 FileReadTool priming (#305)

Store 2 (Fixes): ConceptCompilerProjection already tracked the
unconfirmed(validatedFixes>=1)/falsified(contradicted)/confirmed(promoted)
lifecycle as data, but only confirmed (>=threshold) clusters were ever
delivered. unconfirmedFixEntries reactively matches the CURRENT retry's
classKey against that state and injects a soft one-shot hint (below
threshold) or steer-away (contradicted) before hard promotion — wired
into stage context build in SessionOrchestratorExecution.kt.

Store 3 (Plan-shapes): already shipped as SessionOrchestratorPlanPatterns.kt
(deterministic keyword-Jaccard over eventStore.allEvents(), no embedder
needed) — confirmed complete, no new code required.

FileReadTool hot-path extension to Store 1: a whole-file read now primes
the cross-session ObservationStore (when wired) the same way the write
path already does, so a later describeCached lookup for the same content
hash is warm even if the file was only read, not written, this session.

apps/server/src/main/kotlin/com/correx/apps/server/Main.kt

@@ -344,9 +344,12 @@ fun main() {
         ),
     )
 
+    val observationStore = InfrastructureModule.createObservationStore()
     val wsToolRegistryProvider = WorkspaceToolRegistryProvider { workspace ->
         val wsRegistry = InfrastructureModule.createToolRegistry(
-            buildToolConfigForWorkspace(workspace, shellAllowedExecutables, toolsConfig, researchToolConfig),
+            buildToolConfigForWorkspace(
+                workspace, shellAllowedExecutables, toolsConfig, researchToolConfig, observationStore,
+            ),
             extraTools = extraTools,
         )
         val wsExecutor = DispatchingToolExecutor(wsRegistry)
@@ -390,7 +393,6 @@ fun main() {
         semanticReviewer = SemanticReviewerImpl(inferenceRouter),
     )
     val decisionJournalRepository = InfrastructureModule.createDecisionJournalRepository(eventStore)
-    val observationStore = InfrastructureModule.createObservationStore()
     val defaultOrchestrationConfig = OrchestrationConfig(
         sandboxRoot = sandboxRoot,
         defaultSystemPromptPath = toolsConfig.defaultSystemPromptPath,
@@ -963,6 +965,7 @@ private fun buildToolConfigForWorkspace(
     shellAllowedExecutables: Set<String>,
     toolsConfig: com.correx.core.config.ToolsConfig,
     research: com.correx.infrastructure.tools.ResearchToolConfig,
+    observationStore: com.correx.core.context.observation.ObservationStore? = null,
 ): ToolConfig = ToolConfig(
     research = research,
     shell = ShellConfig(
@@ -974,6 +977,8 @@ private fun buildToolConfigForWorkspace(
         enabled = toolsConfig.fileReadEnabled,
         allowedPaths = workspace.allowedPaths,
         workingDir = workspace.workingDir,
+        observationStore = observationStore,
+        repoRoot = workspace.workingDir?.toString(),
     ),
     fileWrite = FileWriteConfig(
         enabled = toolsConfig.fileWriteEnabled,