feat: respect //nolint directives (diff mode)

[peczenyj]

Diff mode now respects //nolint directives by default, matching golangci-lint: a struct whose type declaration carries a recognized directive is suppressed.

• Default tokens: the named fieldalignment plus a bare //nolint (always honored).
• -nolint-linters (default "fieldalignment") customizes the named token set, e.g. -nolint-linters=fieldalignment,betteralign.
• -show-nolint reveals suppressed structs (audit mode).
• Detection reads the type's doc comment (TypeSpec.Doc / grouped GenDecl.Doc) and any comment on the type's opening line — catching a trailing type T struct { //nolint, which the AST doesn't attach to TypeSpec.Comment (matched by line, like golangci-lint).
• Inspect mode ignores these directives (a //nolint:fieldalignment is about the finding, which inspect doesn't produce).

New common.Options fields RespectNolint/NolintLinters carry the policy into internal/align; the short-circuit sits beside the existing filters in buildFinding.

Tests: 3 in internal/align (doc directive suppresses, unrelated //nolint:errcheck doesn't, bare trailing //nolint suppresses, configurable token set) + 4 in internal/app (hidden by default, -show-nolint reveals, -nolint-linters opt-out, inspect ignores). task ci green (103 tests).

⚠️ Stacked (base feature/threshold) during the GitHub Actions incident; base retargets to devel as the stack merges.

Closes #32

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.10989% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.05%. Comparing base (2a38ce5) to head (5e04c32).

Files with missing lines	Patch %	Lines
internal/align/nolint.go	87.67%	6 Missing and 3 partials ⚠️

Additional details and impacted files

@@                  Coverage Diff                  @@
##           feature/threshold      #39      +/-   ##
=====================================================
- Coverage              85.71%   85.05%   -0.67%     
=====================================================
  Files                     10       11       +1     
  Lines                    721      970     +249     
=====================================================
+ Hits                     618      825     +207     
- Misses                    65      104      +39     
- Partials                  38       41       +3     

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