Add knowledge-base inventory and health audit

[WalksWithASwagger]

Context

The KK knowledge base is now large enough to be a product asset and a product risk. WhisperForge needs to show what exists, what changed, and what may be stale, duplicate, private, or confusing.

Source: docs/WHISPERFORGE-MASTER-PLAN-2026-05-18.md (wf-kb-inventory, Phase 2).

Linear: BC-222.

Acceptance Criteria

• Add an inventory command or UI panel for profile knowledge-base files with filename, size, modified time, rough token count, and detected role.
• Flag likely stale, duplicate, empty, oversized, or private/sensitive files using conservative heuristics.
• Summarize profile-level health in a compact report that can be exported or copied.
• Keep existing profile loading behavior unchanged for valid current profiles.
• Document how agents should use the audit before changing prompts or KB docs.

Tests/Evals

• Unit tests with fixture KB folders for empty, duplicate, stale, and oversized cases.
• No external API calls required.

Verification

• make test
• python3 -m json.tool ops/roadmap/features.json
• git diff --check

Agent Instructions

Use structured filesystem metadata and existing prompt/profile helpers where possible. Avoid judging content quality too aggressively; surface signals, not absolute truth.

Out of Scope

Do not rewrite or delete knowledge-base files automatically.

[WalksWithASwagger]

PR #26 is ready for review: https://github.com/WalksWithASwagger/spektorAI/pull/26\n\nThis slice adds KB inventory/health auditing with stale, duplicate, empty, oversized, and private-looking signals plus JSON download/copy support. Verified with make test, make eval-fixture, ui_smoke, make smoke, local Playwright UI checks, git diff --check, and ops/roadmap/features.json validation.