docs(runtime): document composing actions with unwrap() for Result

[jhnns]

Summary

• Adds an "Actions that return a Result" section to the runtime README, showing how to compose an action with unwrap() from @peerigon/typescript-toolkit/unwrap so a Result-returning fn throws instead of needing manual unwrapping at every call site.

Test plan

• npm run test:unit
• npm run test:types
• npm run test:lint
• npm run test:format
• npm run test:build:size

🤖 Generated with Claude Code

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commit: d89d9d6

[coveralls]

Coverage Report for CI Build 30847129604

Coverage remained the same at 95.627%

Details

• Coverage remained the same as the base build.
• Patch coverage: No coverable lines changed in this PR.
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	575
Covered Lines:	562
Line Coverage:	97.74%
Relevant Branches:	294
Covered Branches:	269
Branch Coverage:	91.5%
Branches in Coverage %:	Yes
Coverage Strength:	14.89 hits per line

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💛 - Coveralls