chore(release): prepare v0.6.0

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Summary

• Cut the stable v0.6.0 CLI version from the existing v0.6 development line.
• Freeze the fixed v0.6 release contents: multiple time-separated episodes, finding_id / episode_index, report schema v3, parser handler registry, property/fuzz coverage, util-linux login, and audit-only privilege auth signals.
• Move the release entries out of Unreleased and align the v0.6 release note with the shipped contract.

Validation

• Windows/MSVC Release build from a fresh temporary build directory.
• ctest --test-dir ... -C Release --output-on-failure: 6/6 passed.
• Independent JSON consumer: CONSUMER_COMPATIBILITY_OK schema=loglens.report.v3 schema_version=3 findings=2 episodes=1,2.
• actionlint passed for all workflows.
• git diff --check and JSON/privacy path scans passed.

Release protocol

• Design decision: keep the numeric CMake project version at 0.6.0 and use an empty suffix for the stable release; the existing suffix mechanism remains available for prerelease builds.
• Main risk: downstream report consumers must migrate from loglens.report.v2 / schema_version: 2 to v3 and use stable finding identity fields.
• Compatibility impact: report JSON changes to schema v3; CLI parsing and the optional CSV contract remain unchanged.
• Rollback path: revert 6f99de5 and remove the release tag/release if the release verification gates fail.
• Issues Backlog: decide configurable semantics for privilege auth failure signals #100–Backlog: evaluate report surface for non-counting auth signals #102 are deliberately excluded from this release.