Add Phase 5 Kotlin desktop app: Compose Multiplatform with gRPC client

Kotlin/Compose Desktop application under desktop/ with:
- Gradle build: Kotlin 2.1, Compose 1.8, gRPC/Protobuf codegen, detekt
- ExoClient: gRPC client for both ArtifactService and KnowledgeGraphService
- Obsidian-style layout: collapsible tree sidebar, contextual main panel
- Five view modes: artifact detail, note editor, search results, catalog,
  graph (stub)
- Unified search bar with selector prefix support
- Command palette (Ctrl+Shift+A) for quick actions
- Menu bar with keyboard shortcuts (Ctrl+I/L/F/Q)
- Dark Material 3 theme
- Detekt lint config with Compose/test naming exceptions
- Unit tests for AppState and model types

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

desktop/detekt.yml

@@ -0,0 +1,63 @@
+# Detekt configuration for exo-desktop.
+# Strict: treat issues as errors, not warnings.
+
+build:
+  maxIssues: 0
+
+complexity:
+  LongMethod:
+    threshold: 60
+  LongParameterList:
+    functionThreshold: 8
+    constructorThreshold: 10
+  ComplexCondition:
+    threshold: 5
+  TooManyFunctions:
+    thresholdInFiles: 25
+    thresholdInClasses: 20
+    thresholdInInterfaces: 15
+
+naming:
+  FunctionNaming:
+    # Compose uses PascalCase for @Composable functions.
+    # Tests use backtick names.
+    excludes: ['**/ui/**', '**/test/**']
+  MatchingDeclarationName:
+    active: false
+  TopLevelPropertyNaming:
+    constantPattern: '[A-Z][A-Za-z0-9_]*'
+
+style:
+  MagicNumber:
+    ignoreNumbers:
+      - '-1'
+      - '0'
+      - '1'
+      - '2'
+      - '5'
+      - '100'
+      - '9090'
+    ignorePropertyDeclaration: true
+    ignoreCompanionObjectPropertyDeclaration: true
+    ignoreAnnotation: true
+    ignoreEnums: true
+  MaxLineLength:
+    maxLineLength: 120
+    excludeCommentStatements: true
+  WildcardImport:
+    active: true
+    excludeImports:
+      - 'kotlinx.coroutines.*'
+  ReturnCount:
+    max: 4
+  UnusedPrivateMember:
+    allowedNames: '(_|ignored|expected)'
+
+exceptions:
+  TooGenericExceptionCaught:
+    active: true
+    exceptionNames:
+      - 'Exception'
+      - 'RuntimeException'
+      - 'Throwable'
+