feat: add HTML inventory report generator with focus/story views

[shrwnsan]

Summary

Adds scripts/generate-report.py — a zero-dependency Python 3.10+ script that reads bumblebee's inventory.ndjson output and generates a self-contained HTML report with Story/Focus views, dark/light themes, scroll-spy navigation, and inline data visualization.

Motivation

bumblebee scan emits structured NDJSON, but there is no built-in reporting UX. This script provides an immediate, visual report for ecosystem distribution, lifecycle-script risk, version sprawl, top projects, confidence, sources, and scan roots — with no setup beyond Python 3.

Changes

• New: scripts/generate-report.py (single-file, stdlib-only)
• Updated: .gitignore (report.html ignored)

Notable updates in this branch

• Focus view is now the default (Story view remains one click away)
• Added tabbed section navigation in Focus view with hash/localStorage sync
• Refactored row aggregation for lower string/memory churn (list.append + join, leaner multi-version aggregation)

Screenshots

Dark mode

Light mode

Testing

• gofmt -l .
• go vet ./...
• go test -race ./...
• go build -buildvcs=false ./cmd/bumblebee
• ./bumblebee selftest
• Manual browser verification: Story/Focus toggle, tab switching, theme toggle, hash/localStorage persistence

Checklist

• No new dependencies
• Generated report.html remains gitignored