APP-93: Simplify and focus Truffile agent guidance

[temp-deepshard]

Why

A user should be able to give an existing coding agent a Truffle goal. The agent should own setup and local work, then pause only at a real device or human boundary.

Changes

• replaces the setup checklist with a short goal-first prompt
• tells the agent to load only the copied skills needed for the task
• runs doctor, continues device-independent work, and asks for help only when blocked
• names the human boundaries: Symphony onboarding, physical approval, credentials, deployment, and destructive actions
• adds a directly discoverable container-execution section to the CLI skill

Validation

• exact pushed commit b9c9051: 159 passed
• all four bundled skill files validate
• isolated Python 3.12 wheel loaded the skills, diagnosed the no-device state, and continued through all three app shapes and seven example dry-runs
• final combined suite: 216 passed, 9 subtests passed
• automated CI: none configured; validation was run manually

Depends on: #41, #42, #43, #44, and docs #6

Docs: deepshard/docs#5

Linear: APP-93