Document Maven plugin and goal reference

[diegosilval]

Implements Website Phase 4 for Eclipse Coffee Builder.

Changes include:

• document the Maven Plugin operating model and invocation syntax
• document all 12 functional goals and the generated help goal
• group goals by capability area
• document verified parameters, defaults, prerequisites, outputs, and caveats
• document datasource declaration modes and name:value properties syntax
• document add-forms-from-entities prerequisite on add-domain-models outputs
• document embedded configuration behavior
• document runtime goal caveats for GlassFish and Payara Micro
• document OpenAPI and Faces behavior from the current implementation
• add goal-category pages and a dedicated Goal Reference layout
• add subpath-aware Solstice navbar behavior

Validation:

• complete monorepo mvn install succeeds
• 149 plugin tests pass
• four archetype integration scenarios pass
• representative plugin goals were exercised against temporary Jakarta EE 11 projects
• functional-goal inventory matches the generated plugin descriptor
• user-facing parameter properties, required flags, types, and defaults match implementation
• Hugo root and /preview/ builds pass with --panicOnWarning
• internal routes, anchors, source links, prohibited-content scans, UTF-8, and whitespace checks pass

This documents the current 0.1.0-SNAPSHOT development behavior and does not claim stable Maven Central availability.