docs: align setup and configuration references with current runtime

[aviggiano]

The setup and configuration docs contain examples that current Ultrafuzz rejects and omit steps needed to use a source build. This updates the documentation to match the current parser, stock agents, and Smithers migration behavior.

• Use ultrafuzz.config.v2 and remove conflicting scalar/table definitions of models.default from the examples.
• Replace the obsolete OpenRouter-via-CodexAgent setup with the dedicated stock agent's behavior, and correct canonical credential-variable guidance, including the Pi and tutorial descriptions.
• Include OpenCodeAgent and PiAgent in the supported-agent list.
• Document Node, pnpm, Bun, Git, Foundry, and agent CLI prerequisites; explain how to invoke the built CLI through a shell function or its absolute entrypoint.
• Describe the recognized Smithers 0.32.0 and 0.34.0 manifest migrations to 0.35.0, including preservation of unrecognized adapters.

Validation: pnpm -w docs:check, Prettier and markdownlint-cli 0.49.0 checks for all four changed files (using the pinned Super-Linter configuration), git diff --check, and pnpm --filter @ultrafuzz/cli... build pass. All 18 TOML blocks in the two configuration pages pass the current config parser. The documented shell function successfully displays CLI help both from the repository root and after changing directories. No runtime behavior changes.

Greptile Summary

Aligns setup and configuration documentation with the current runtime behavior.

• Corrects configuration schema and model-profile examples.
• Documents current stock agents and canonical credential variables.
• Clarifies source-build prerequisites and CLI invocation.
• Describes recognized Smithers manifest and adapter migrations.

Confidence Score: 5/5

The documentation-only changes appear safe to merge.

No actionable new issues or outstanding rule violations were identified.

Important Files Changed

Filename	Overview
docs/config.md	Updates stock-agent, credential, model-profile, and OpenRouter guidance to match current validation and generated adapters.
docs/reference/cli.md	Clarifies recognized Smithers manifest migrations and preservation of customized or unrecognized adapters.
docs/reference/configuration.md	Corrects the schema version and removes invalid conflicting TOML definitions for the default model profile.
docs/tutorials/first-campaign.md	Documents source-build prerequisites, reliable CLI invocation, and canonical OpenRouter credential configuration.

_{Reviews (2): Last reviewed commit: "docs: correct OpenRouter heading level" | Re-trigger Greptile}