Document tool output schema discovery

[mindbomber]

Summary

• add output schema discoverability guidance to Factor 4 so tool contracts describe both inputs and returned structured data
• connect output schemas back to Factor 3's context-window guidance for result projection and token efficiency
• keep the change scoped to docs for issue [Proposal] Standardize Discovery of Tool Output Schemas #12FactorTools #22 without claiming a protocol mandate or production guarantee

Tests

• git diff --check
• inspected repository root: no package manifest or test harness is present for this docs-only change

Part of #22.

[CLAassistant]

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