Add optional Changelog root element to Bjoern specs

[Copilot]

Adds a new optional Changelog free-text field to the .zgr spec format for documenting changes, background, and technical rationale. When present, it is surfaced in both generated Javadoc and AsciiDoc output. The field supports YAML multiline block scalars (| and >) for arbitrarily long content.

Spec format

Single-line:

Feature: My Feature
Changelog: "Describes what changed and why."
Scenarios:
  - Scenario: ...

Multiline (YAML literal block scalar):

Feature: My Feature
Changelog: |
  First line of the changelog.
  Second line with more details.
Scenarios:
  - Scenario: ...

Changes

• Parser model (BjoernZGRModell, Bjoern) — new Changelog field with full @JsonProperty wiring and constructor mapping
• Javadoc generation (BjoernFeatureTestClassBuilder) — appends @Changelog <text> to the abstract class Javadoc when present
• AsciiDoc template (asciidoc.ftlh) — renders Changelog: <text> after the Reference line, guarded by a null/empty check; uses changelogAsAsciidoc for sanitized output
• Sanitization (Bjoern) — getChangelogAsAsciidoc() applies AsciidocReplacer.replace() to escape AsciiDoc-special characters (e.g. pipe | → \|)
• Validator (BjoernKeywords, InvalidKeywordValidation) — added Changelog: as a recognized keyword; continuation lines inside a Changelog: | or Changelog: > block scalar are exempt from keyword validation
• README — documents the new field and its rendering behavior in Java and docs

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Neues Root Element "changelog"</issue_title>
<issue_description># Anforderung

Neues Root‑Element "changelog" hinzufügen.
Dieses Feld dient der Ablage eines beliebig langen Freitextes, der Änderungen, Hintergründe oder technische Beweggründe zur Spezifikation beschreibt.
Der Inhalt soll später automatisiert in Docs und Javadoc mit generiert werden.

---

Umsetzung

• In der Bjoern‑Spezifikation ein neues Feld changelog hinzufügen

  • Typ: Textfeld / textarea
  • Inhalt: beliebig lang
  • Keine semantische Prüfung notwendig
  • Feld ist optional

• Im Code:

  • Den Inhalt des Changelogs in der Javadoc der zugehörigen Spezifikations‑Klasse hinterlegen
    • Annotation/Tag: @Changelog oder internes Äquivalent

• In den Docs:

  • Den Changelog‑Text am Ende der Einleitung nach dem Featurenamen einfügen
  • Generierung erfolgt nur, wenn auch tatsächlich ein changelog im Root vorhanden ist</issue_description>

<agent_instructions>also change the README!!!</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Neues Root Element "changelog" #91

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[Mehtrick]

stelle sicher dass das Changelog sanitized ist

[Copilot]

Pull request overview

Adds an optional root-level Changelog field to the .zgr specification format and wires it through parsing, validation keywords, Java test-class Javadoc generation, and AsciiDoc documentation output.

Changes:

• Extend YAML + internal models to carry Changelog and propagate it into generators.
• Render changelog in generated artifacts (AsciiDoc template + @Changelog Javadoc tag).
• Add/adjust tests and docs for the new keyword/field.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/main/java/de/mehtrick/bjoern/parser/modell/BjoernZGRModell.java	Adds @JsonProperty("Changelog") field + accessors to YAML model.
src/main/java/de/mehtrick/bjoern/parser/modell/Bjoern.java	Adds internal changelog field and constructor mapping from YAML model.
src/main/java/de/mehtrick/bjoern/generator/builder/BjoernFeatureTestClassBuilder.java	Emits @Changelog in generated feature class Javadoc.
src/main/resources/asciidoc.ftlh	Outputs Changelog: block in generated AsciiDoc when present.
src/main/java/de/mehtrick/bjoern/parser/validator/validations/BjoernKeywords.java	Registers Changelog: as a valid keyword for validator keyword checks.
src/test/resources/changelog.zgr	New test spec file including Changelog:.
src/test/java/de/mehtrick/bjoern/asciidoc/AsciiDocBuildTest.java	Adds AsciiDoc generation tests for presence/absence of changelog output.
src/test/java/de/mehtrick/bjoern/generator/builder/BjoernFeatureTestClassBuilderTest.java	Adds Javadoc generation test for @Changelog.
src/test/java/de/mehtrick/bjoern/parser/BjoernValidatorTest.java	Updates expected allowed-keyword list to include Changelog:.
README.md	Documents the new optional Changelog field and its outputs.

[Copilot]

stelle sicher dass das Changelog sanitized ist

Added getChangelogAsAsciidoc() to Bjoern.java which applies AsciidocReplacer.replace() (escapes pipe characters). The AsciiDoc template now uses changelogAsAsciidoc instead of the raw value. Done in c3646ab.