Add # typeprof:ignore comment to suppress diagnostics

[mame]

Add a way to suppress TypeProf diagnostics on specific lines via comments, following Steep's # steep:ignore convention.

Syntax

Inline form — suppresses diagnostics whose code range starts on the same line:

def check
  Foo.new.accept_int("str") # typeprof:ignore
end

Block form — suppresses diagnostics between :start and :end:

# typeprof:ignore:start
foo(1, 2)
bar(1, 2)
# typeprof:ignore:end

An unmatched # typeprof:ignore:start extends to the end of the file.

Why ignore (and not disable/enable)

To match Steep's existing convention so that users of the Ruby type-checker ecosystem only need to remember one keyword:

form	Steep	this PR
inline	# steep:ignore	# typeprof:ignore
block start	# steep:ignore:start	# typeprof:ignore:start
block end	# steep:ignore:end	# typeprof:ignore:end

Implementation

• AST.collect_ignore_ranges (in lib/typeprof/core/ast.rb) scans Prism comments at parse time and returns a list of ignored line ranges.
• ProgramNode stores those ranges and filters them out in each_diagnostic based on each diagnostic's starting line.

The whole feature is ~40 lines plus tests.

Relation to #306

This PR supersedes #306 by @x-smasato, which proposed the same feature with # typeprof:disable / # typeprof:enable keywords and a dedicated Diagnostic::DisableDirective::Scanner / Filter module pair.

Differences from #306:

• Keyword renamed to typeprof:ignore / :start / :end to align with Steep (see above).
• The Scanner/Filter classes are inlined as a small helper in ast.rb and a few lines in ProgramNode#each_diagnostic, since the logic is short enough that splitting it across files felt heavier than the implementation deserved.

@x-smasato's authorship is preserved as Co-Authored-By on the first commit. Thanks to them for the original proposal and design — the structure (scan at parse time, filter at ProgramNode#each_diagnostic) is borrowed from #306.

I'll close #306 once this lands.