feat(comments): add typed visibility tool inputs and outputs - #3384

Summary

Migrate the shared hide/unhide comment-visibility factory to typed inputs and results for all six issue-comment, pull-request review-comment, and review tools. Legacy text stays unchanged; output schemas and structured results are visible only on MCP protocol 2026-07-28 or later.

Why

Dependent layer above #3377, using the typed registration and legacy normalization foundation from #3371. No issue is closed by this layer; #3360 remains unchanged and open.

What changed

• Add typed comment visibility input and output handling while retaining target-specific schemas, exact descriptions, required identifiers, numeric minimums, permissions and feature rules.
• Normalize legacy numeric-string IDs and classifier casing through the foundation hook before SDK validation; preserve ignored arguments and rejection semantics.
• Add fresh-session wire tests for both negotiated protocol versions, all hide/unhide targets, output conformance, schema equivalence, API errors and feature/scope/read-only gates; update only the six related snapshots.

MCP impact

• No tool or API changes
• Tool schema or behavior changed
• New tool added
  Output schemas and typed structured content are added for modern clients. Existing input schemas and legacy success text remain unchanged; errors remain errors without structured success output.

Prompts tested (tool changes only)

• Mocked wire-call equivalents of “Hide issue comment 1 as off-topic”, “Unhide inline pull request review comment 2”, and “Hide/unhide review 3 on pull request 42”; these are automated protocol tests, not live GitHub prompt runs.

Security / limits

• No security or limits impact
• Auth / permissions considered
• Data exposure, filtering, or token/size limits considered
  The existing repo scope requirement, granular feature flags, read-only filtering, permission descriptions and API calls are preserved. Structured output contains the same node ID and visibility fields as existing text; invalid inputs and failed mutations never yield successful structured output.

Tool renaming

• I am renaming tools as part of this PR (e.g. a part of a consolidation effort)
  • I have added the new tool aliases in deprecated_tool_aliases.go
• I am not renaming tools as part of this PR
  All six tool names are unchanged.

Note: if you're renaming tools, you must add the tool aliases. For more information on how to do so, please refer to the official docs.

Lint & tests

• Linted locally with ./script/lint
• Tested locally with ./script/test
./script/lint was replaced by the requested Go-compatible change-only linter because the pinned linter is incompatible with Go 1.27.1. gofmt -w pkg/github/comment_minimize.go pkg/github/comment_minimize_test.go completed successfully. /tmp/golangci-lint/golangci-lint run --new-from-rev=484c813c3b3a7d84a38dbe8365299d1b2090e982 passed with 0 issues. script/test passed (go test -race ./...). go test ./pkg/github -run 'Test_CommentVisibilityToolSchemas|TestCommentVisibilityTypedInputSchemaMatchesLegacy|TestCommentVisibilityProtocols|TestCommentVisibilityProtocolGating|TestNormalizeCommentVisibilityInput|Test_HideAndUnhideComments' -count=1 passed. UPDATE_TOOLSNAPS=true go test ./pkg/github -run 'Test_CommentVisibilityToolSchemas|TestGranularToolSnaps' -count=1 passed when updating the six relevant snapshots. Live PAT-dependent e2e tests were not run.

Docs

• Not needed
• Updated (README / docs / examples)
  script/generate-docs passed; all generated documentation remained unchanged. Input schema and tool names/descriptions are unchanged, and the related output snapshots document the added API surface.