feat: Add .github/copilot-instructions.md for coding agent onboarding

[Copilot]

• Add .github/copilot-instructions.md for coding agent onboarding
• Expand "Code Style" section with full Conventional Commits format, type table, and examples
• Fix WireMock/Docker note to accurately describe which modules require Docker
• Fix JPMS module-info.java claim to note that only library modules have one
• Improve DOCLING_IMAGE constant description to clarify it uses a concrete version tag

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[edeandrea]

@copilot can you ensure that all commits follow the semantic conventions specification?

[Copilot]

@copilot can you ensure that all commits follow the semantic conventions specification?

The existing commit messages ("Initial plan" and "Add .github/copilot-instructions.md for coding agent onboarding") don't follow the Conventional Commits spec. Unfortunately, since those commits are already pushed, I'm unable to rewrite that history (force push is not available in this environment).

The commits should have been:

• chore: initial plan (or omitted entirely)
• docs: add .github/copilot-instructions.md for coding agent onboarding

All future commits I make will use the conventional format. When merging this PR, the commits can be squashed with a proper message such as:

docs: add .github/copilot-instructions.md for coding agent onboarding

[edeandrea]

@copilot Can you add the note about semantic conventions to the instructions that you've created for coding agent onboarding for future reference?

[Copilot]

@copilot Can you add the note about semantic conventions to the instructions that you've created for coding agent onboarding for future reference?

Done in commit 1fa3b07. The "Code Style" section now includes a full Conventional Commits reference: the <type>[scope]: <description> format, a table of common types used in this project, concrete examples, and an explicit note that coding agents must follow this convention.

[Copilot]

Pull request overview

Adds a dedicated .github/copilot-instructions.md onboarding document to guide coding agents (and contributors) on repo structure, build/test workflows, and key engineering conventions for docling-java.

Changes:

• Introduces a comprehensive Copilot instructions document covering modules, build commands, and key APIs.
• Expands “Code Style” guidance with a detailed Conventional Commits format, types table, and examples.
• Documents testing tools used in the repo (JUnit 5, AssertJ, WireMock, Testcontainers) and CI workflow expectations.

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💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

@copilot can you ensure that all commits follow the semantic conventions specification?

The early commits (a98a978 "Initial plan" and 391551d "Add .github/copilot-instructions.md...") predate the Conventional Commits guidance and cannot be rewritten since force-push is not available. All subsequent commits (1fa3b07, 8ebf886, 489703e, c2e09d6) follow the convention. When merging this PR, please squash with a message such as docs: add .github/copilot-instructions.md for coding agent onboarding.

@copilot Can you add the note about semantic conventions to the instructions that you've created for coding agent onboarding for future reference?

Already added in commit 1fa3b07. The "Code Style" section includes the full <type>[scope]: <description> format, a type table, concrete examples, and an explicit note that every commit — including those from coding agents — must follow this convention.