integrating-jupiter: add diagnostics for suspicious empty Portfolio /positions responses

[amitkarpe]

Context

While using the integrating-jupiter skill (Portfolio playbook), /portfolio/v1/positions/{address} returned a 200 with:

• elements: []
• fetcherReports: []
• tokenInfo: {}

This occurred consistently across multiple wallets, including the docs sample wallet.

Related docs issue: jup-ag/docs#828

Why this impacts the skill

Current guidance says to treat empty positions as valid state, which is generally correct. But when elements=[] and fetcherReports=[] for multiple addresses, this can indicate a suspicious backend/indexing condition rather than a truly empty portfolio.

In this state, an agent following the skill strictly may incorrectly conclude everything is fine.

Request

Please consider adding a Portfolio troubleshooting note in skills/integrating-jupiter/SKILL.md:

1. Define an "empty-but-suspicious" condition (e.g., elements=[] + missing/empty fetcherReports).
2. Recommend retries with backoff and /portfolio/v1/platforms sanity check.
3. Recommend checking status/known incidents and escalating with request metadata when persistent.
4. Clarify that docs/sample wallet returning the same empty shape is a signal to escalate, not wallet-specific.

This would make agent behavior safer and reduce false "no positions" conclusions.