refactor: wave 1 - extract leaf modules, rename catch-all files, split index.ts hooks

- Split 25+ index.ts files into hook.ts + extracted modules
- Rename all catch-all utils.ts/helpers.ts to domain-specific names
- Split src/tools/lsp/ into ~15 focused modules
- Split src/tools/delegate-task/ into ~18 focused modules
- Separate shared types from implementation
- 155 files changed, 60+ new files created
- All typecheck clean, 61 tests pass

src/shared/model-resolution-types.ts

@@ -0,0 +1,30 @@
+import type { FallbackEntry } from "./model-requirements"
+
+export type ModelResolutionRequest = {
+  intent?: {
+    uiSelectedModel?: string
+    userModel?: string
+    categoryDefaultModel?: string
+  }
+  constraints: {
+    availableModels: Set<string>
+  }
+  policy?: {
+    fallbackChain?: FallbackEntry[]
+    systemDefaultModel?: string
+  }
+}
+
+export type ModelResolutionProvenance =
+  | "override"
+  | "category-default"
+  | "provider-fallback"
+  | "system-default"
+
+export type ModelResolutionResult = {
+  model: string
+  provenance: ModelResolutionProvenance
+  variant?: string
+  attempted?: string[]
+  reason?: string
+}