Add MCP outline pagination and projection controls

[Widthdom]

Summary

• Add CLI-compatible fields, sort, limit, cursor, and maxBytes controls to the MCP outline tool.
• Preserve deterministic page boundaries and hierarchy metadata within one SQLite read snapshot, and point follow-up excerpts at the symbols actually returned on each page.
• Add large/deep/empty/projection/byte-boundary/stale-cursor/schema coverage.

Documentation and changelog

• Update the English and Japanese sections of README.md, docs/USER_GUIDE.md, docs/DEVELOPER_GUIDE.md, and docs/TESTING_GUIDE.md.
• Add changelog.d/unreleased/4897.added.md.

Validation

• dotnet restore CodeIndex.sln
• dotnet build CodeIndex.sln -c Release -p:UseSharedCompilation=false --no-restore (net8/net9, 0 warnings, 0 errors)
• Issue Add pagination and projection controls to MCP outline #4897 targeted tests on net8/net9 (4/4 each after the final review fix)
• Full Release suite: net8 passed; net9 had one unrelated timing failure in IndexCommandRun_WatchActiveUpdate_PropagatesTopLevelCancellation_Issue4591, and its exact isolated rerun passed
• make lint
• dotnet run --project tools/CodeIndex.Changelog -- check
• git diff --check
• Local CodeIndex status reports the committed HEAD current and the index fresh
• Codex adversarial review completed; both actionable findings were fixed and regression-tested

An additional review-time Debug full-suite attempt encountered unrelated workspace-permission and macOS keychain environment failures; the required Release build and issue-focused net8/net9 tests remained green.

Follow-up candidates

None.

Fixes #4897