Drop nounset (set -u) flag — incompatible with env var checks (#27)

The autonomous refactoring added `set -euo pipefail` but the scripts
check optional env vars with `[[ -n "$VAR" ]]` which is a fatal error
under nounset when the var isn't set (e.g. SPRITE_NAME, OPENROUTER_API_KEY).

Fix: downgrade to `set -eo pipefail` across all 42 affected files.

Co-authored-by: Sprite <noreply@sprite.dev>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cli/tsconfig.json

@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "outDir": "dist",
+    "rootDir": "src",
+    "types": ["bun"]
+  },
+  "include": ["src"]
+}