Add OCI Code-only Functions deployment and archive generation skills

Summary

Extend the existing OCI Functions skills with public guidance for creating validated code-only archives and deploying code-only Functions.

Scope

Add:

• A code-only archive creation skill for Java, Python, Node.js, and Go.
• Code-only scaffold deployment guidance.
• Immutable prebuilt ZIP deployment guidance.
• OCI domain routing updates.

Requirements

• Use public Oracle documentation only.
• Verify that all code-only Fn CLI/API behavior is publicly documented.
• Keep container deployment behavior unchanged.
• Start with read-only validation where possible.
• Make every mutating action explicit and confirmation-gated.
• Add ## Sources to every new or changed Functions Markdown file.
• Do not include internal URLs, tenancy information, roadmap details, unpublished CLI behavior, or credentials.

Acceptance criteria

• Add a customer-facing code-only archive skill.
• Extend oci-functions-deploy with code-only routing.
• Preserve the existing container deployment workflow.
• Update oci/SKILL.md and root navigation.
• Add public Oracle sources.
• Add and pass regression tests.
• Run formatting, shell syntax, and contract checks.