fix(resolver): JSON-serialize array params in Mustache body templates…

[eskenazit]

Related Issue

Closes #213

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What does this PR do?

Resolver.resolveMustacheTemplate was using JMustache with default settings, causing two issues:

1. Collection and Object[] values were substituted via toString(), producing [CREW-001, CREW-003] (no quotes) — invalid JSON when inserted into a body template.
2. JMustache HTML-escapes by default (" → "). Templates here produce JSON/URI output, never HTML, so this escaping corrupted the serialized JSON values.

Fix: JSON-serialize collections using Jackson before substitution, and disable HTML escaping via escapeHTML(false).

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Tests

• ResolverTest#resolveMustacheTemplateShouldJsonSerializeArrayParameters — verifies that a List is properly serialized as a JSON array in the template
• ResolverTest#resolveMustacheTemplateShouldPreserveNonAsciiCharacters — verifies that non-ASCII characters (e.g. ø) are not corrupted by HTML escaping

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Checklist

• CI is green (build, tests, schema validation, security scans)
• Rebased on latest main
• Small and focused — one concern per PR
• Commit messages follow Conventional Commits

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Agent Context (optional)

agent_name: GitHub Copilot
llm: Claude Sonnet 4.6
tool: VS Code Copilot Chat
confidence: high
source_event: step-6 tutorial debug — create-voyage body rendered as invalid JSON
discovery_method: runtime_observation
review_focus: Resolver.java:resolveMustacheTemplate

[jlouvel]

LGTM