feat: replace ad-hoc --json flag with unified --output table|json|yaml

[Copilot]

All CLI list/show commands had a scattered --json boolean with no YAML support and no shared output contract, making scripting inconsistent and blocking future field-filtering work.

Changes

• New src/py_moodle/cli/output.py — centralized output contract:

  • OutputFormat(str, Enum): table | json | yaml
  • emit(data, output_format, table_fn): dispatches to JSON/YAML serialization or a caller-supplied rich table renderer

• Updated 8 commands across courses, categories, sections, users, and modules — --json: bool removed, --output: OutputFormat = table added; table rendering refactored into local _render_table closures passed to emit()

• pyyaml added as an explicit runtime dependency (was already present transitively)

• 19 new unit tests in tests/unit/test_output_format.py covering emit() behavior for all three formats, unicode preservation, missing table_fn guard, and help-text assertions for each updated command

Usage

py-moodle courses list                   # table (default, unchanged)
py-moodle courses list --output json     # replaces --json
py-moodle courses list --output yaml     # new

Adding --output support to a new command is now one import + one emit() call.

---

📍 Connect Copilot coding agent with Jira, Azure Boards or Linear to delegate work to Copilot in one click without leaving your project management tool.