chore: add knip for unused export/dependency detection

Adds `pnpm check:unused` script powered by knip. Initial run finds
17 unused files, 3 unused deps, 96 unused exports, and 117 unused
exported types — all candidates for cleanup.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

knip.json

@@ -0,0 +1,30 @@
+{
+  "$schema": "https://unpkg.com/knip@latest/schema.json",
+  "ignore": [".claude/**", "backups/**", "samples/**"],
+  "ignoreDependencies": ["@capakraken/eslint-config", "@capakraken/tsconfig", "turbo"],
+  "ignoreBinaries": ["playwright"],
+  "workspaces": {
+    "apps/web": {
+      "ignore": ["src/**/*.test.{ts,tsx}", "e2e/**"]
+    },
+    "packages/shared": {},
+    "packages/db": {
+      "entry": [
+        "src/index.ts",
+        "src/seed*.ts",
+        "src/reset-*.ts",
+        "src/generate-*.ts",
+        "src/update-*.ts",
+        "src/*.mjs"
+      ],
+      "ignoreDependencies": ["exceljs"]
+    },
+    "packages/engine": {},
+    "packages/staffing": {},
+    "packages/application": {},
+    "packages/api": {},
+    "tooling/eslint": {
+      "entry": ["src/*.js"]
+    }
+  }
+}

package.json

@@ -14,6 +14,7 @@
     "test:e2e:email": "pnpm --filter @capakraken/web test:e2e:email",
     "test:scripts": "node --test scripts/*.test.mjs",
     "audit": "pnpm audit --audit-level=high",
+    "check:unused": "knip",
     "check:architecture": "node ./scripts/check-architecture-guardrails.mjs",
     "check:exports": "node ./scripts/check-workspace-exports.mjs",
     "check:imports": "node ./scripts/check-workspace-imports.mjs",
@@ -40,6 +41,7 @@
     "@capakraken/eslint-config": "workspace:*",
     "@capakraken/tsconfig": "workspace:*",
     "husky": "^9.1.7",
+    "knip": "^6.3.1",
     "lint-staged": "^16.4.0",
     "prettier": "^3.3.3",
     "turbo": "^2.3.3",