feat: resolve instance paths against model data (RS 3002 evaluation half)

[ronaldtse]

Instance-path resolution: the RS 3002 evaluation half

The gem parses instance data paths (RS 3002 "LutaML path for instance
data") — grammar, filters, conditions, 87 green examples — but
resolution was deliberately out of scope: InstancePath#match?
raises rather than silently matching names while ignoring conditions.

This adds the evaluation half, without touching the parser, the AST,
or a single existing example:

• Lutaml::Path::Resolver walks InstancePath#steps over real
  model data: lutaml-model Serializable instances (attribute readers
  via the class contract), plain hashes, and their collections.
  Base steps anchor the root, attribute steps read named children
  (segment patterns through the existing fnmatch contract), **
  selects every descendant, and a step's condition filters the
  candidates.
• Lutaml::Path::Filter::ConditionEvaluator evaluates the
  Condition AST the parser already produces: comparisons (=, !=,
  >, <, >=, <= with numeric coercion when both sides are
  numeric), list membership (in), existence, &&/||/! with
  parentheses and nesting, and wildcard values via
  File.fnmatch(..., FNM_EXTGLOB) — matching the segment matcher's
  own glob semantics.
• API: Lutaml::Path.resolve(root, path) and
  InstancePath#resolve(root). Plain chains resolve to a single
  value; filters, patterns, and deep wildcards return collections.
• gemspec: lutaml-model (>= 0.8) joins parslet — resolution
  reads model attributes through the Serializable contract.

The new specs port RS 3002's own instance-data examples (the
contributor / organization / role / docidentifier corpus) end-to-end
against real lutaml-model instances, including hash-rooted data,
chained and nested filters, wildcards, and deep hierarchy matches.

Suite: 98 examples, 0 failures (87 existing + 11 new). Rubocop clean.