Fixes and improvements to evaluation parsing

[tzschmidt]

• Update evaluation format
• Update evaluation parser
• Improve documentation

[Copilot]

Pull request overview

This PR updates the benchmark evaluation XML format and aligns both the writer (runscript) and reader (result parser/classes) to the new structure, with accompanying test and documentation updates.

Changes:

• Extend evaluation/result model to capture richer metadata (e.g., cmdline as {pre, post}, memout, template_options, dist_template/dist_options, per-setting encodings).
• Refactor the result XML parser into smaller helpers with stricter required-attribute handling and clearer errors.
• Update tests, reference XML, and getting-started docs to reflect the new attributes/paths.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/benchmarktool/result/parser.py	Refactors XML parsing into helper methods; parses new attributes (cmdline dicts, memout, template options, setting encodings).
src/benchmarktool/result/result.py	Updates dataclasses (new fields, kw_only=True in several types) to represent the new parsed format.
src/benchmarktool/runscript/runscript.py	Updates XML emission to the new attribute names/structure (e.g., encoding_tag, optional template_options, instance encodings).
tests/result/test_result_parser.py	Adjusts expectations for the new parsed structures/fields.
tests/result/test_result_classes.py	Updates unit tests to match new dataclass signatures/fields (including keyword-only constructors).
tests/runscript/test_runscript_classes.py	Updates XML-string assertions for renamed/added XML attributes and instance encodings.
tests/ref/test_eval.xml	Updates the reference evaluation XML fixture to the new format.
docs/getting_started/workflow/index.md	Rewords/moves an executable-permissions note into an admonition block.
docs/getting_started/gen/runscript.md	Updates example encoding paths and clarifies path relativity.

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[BenKaufmann]

Looks ok to me, but let's wait until @rkaminsk had a look.