[skills] Add weekly signal diff skill pack

[justfinethanku]

Contribution Type

• Skill (/skills)
• Recipe (/recipes)
• Schema (/schemas)
• Dashboard (/dashboards)
• Integration (/integrations)
• Repo improvement (docs, CI, templates)

What does this do?

Adds a universal weekly-signal-diff skill pack for turning a week's worth of market or AI news into a structural diff instead of a summary. The skill starts from 10 suggested categories and 30 suggested companies as a bootstrap scaffold, then reweights the analysis using Open Brain memory, recent priorities, and prior digests. It also includes an optional live-search upgrade path for OpenRouter users who want to use the Perplexity Sonar family for current, source-backed retrieval.

Requirements

• Working Open Brain setup if the user wants memory search and capture
• AI client with reusable skills, rules, or system prompts
• Live web access or a user-provided weekly source set
• Optional: OpenRouter access to the Perplexity Sonar family for stronger automated search

Testing

• Ran local metadata schema validation with check-jsonschema
• Ran a local subset of the OB1 PR gate checks: folder scope, required files, skill artifact presence, README completeness, file-size checks, and internal link resolution
• Reviewed the staged diff and cleared git diff --check
• Did not execute the skill against a live Open Brain connector from this environment, so the PR keeps the testing note honest about that limitation

Checklist

• I've read CONTRIBUTING.md
• My contribution has a README.md with prerequisites, step-by-step instructions, and expected outcome
• My metadata.json has all required fields
• If my contribution depends on a skill or primitive, I declared it in metadata.json and linked it in the README
• I tested this on my own Open Brain instance
• No credentials, API keys, or secrets are included

[github-actions]

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