[deevus]

Summary

Adds gdzig-zlint (ZLint 0.10.0 with the gdzig CODE_STYLE rules) and wires it
into mise and CI. Follow-up to gdzig/gdzig#290.

• Installs github:gdzig/gdzig-zlint 0.6.1 through mise.toml.
• Adds zlint.json from the 0.6.1 template without changing any rule levels.
  The gdzig rules, gdzig-public-docs, and line-length remain at warn;
  homeless-try remains at error.
• Adds mise run lint and a Lint workflow for pushes to main, PRs, and manual runs.
• Applies lint-only edits across the tree: import ordering and placement, an import
  alias, an inferred initializer, test and fixture placement, a trailing comma,
  and the namespace file name. The public XmlDocParser export remains intact.
• No hook system exists in this repo, so none was added. No mise.lock was created.

Verification

• gdzig-zlint .: 0 errors, 37 warnings (before: 0 errors, 60 warnings).
• mise run lint: exits successfully with the same diagnostics.
• Zig 0.15.2 zig build test: passes both before and after these edits. Both runs
  emit the same expected malformed-XML test warning (Bad: error.MalformedXml).
• Zig 0.15.2 zig fmt --check on changed Zig files: passes. The initial whole-tree
  check reported pre-existing unformatted src/cache.zig, src/DocDatabase.zig,
  and src/XmlDocParser.zig; those were formatted only after being changed.
• Remaining warnings: 23 gdzig-public-docs require meaningful API documentation,
  and 14 line-length require separate signature, example, or line wrapping.
  Neither class has a safe mechanical fix within this lint-only rollout.

Notes

• --deny-warnings is intentionally not enabled yet because the existing
  documentation and line length diagnostics still need cleanup.