Add bounded setup command for agent onboarding

[ejntaylor]

Agent onboarding previously required interpreting guide output and manually editing build hooks, which cautious hosted assistants could treat as an unbounded instruction chain.
This adds an idempotent patchstack-connect setup command that scans or reuses the site, manages the widget, preserves and wires existing npm/Bun build scripts, and never runs the project build or protect.
It also improves native package-manager detection, replaces claim-oriented wording with neutral dashboard language, and replaces the 699-byte prompt with an authorization-led request that pre-approves the widget and production hooks while documenting a dependency-first Bolt fallback.
Validation: npm test (391 tests), npm run typecheck, npm run build, npm pack --dry-run --json, node field-test/setup-demo.mjs, the scripted field-test (8/8), and git diff --check.

[coderbuds]

Implements an idempotent setup command that wires build hooks cleanly.

🎯 Quality: 74% Good · 📦 Size: Large — consider splitting if possible

🛡️ Standards: no pre-flight fit check ran for this change — wire assess-change-fit into your coding agents to catch size before opening.

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