chore: install Understand Anything, commit initial knowledge graph

[Atroci]

Summary

• Installed GitHub's "Understand Anything" Claude Code plugin (already present at user scope, v2.7.4) and ran the core /understand analysis pass against this repo.
• Committed the generated knowledge graph at .understand-anything/knowledge-graph.json: 751 nodes, 764 edges, 10 architectural layers, 13-step guided tour, analyzed at commit 86899f4 (v1.8.14).
• .understand-anything/ added to .distignore so it never ships to the WordPress.org release; intermediate/, tmp/, and diff-overlay.json gitignored as scratch/regenerable output.
• CLAUDE.md and docs/README.md now point at the graph so "has ClickTrail ever been mapped against Understand Anything" has a permanent, discoverable answer.

Layers identified

Tracking & Attribution Core, Server-Side Delivery, Admin UI, Form & Platform Integrations, Plugin Bootstrap & Infrastructure, Front-End Assets, Tests & QA, Project Configuration & CI/CD, Documentation & Localization, Dev Tooling (Spec Kit).

Notes / deviations from the original task brief

• The tool's actual default data directory is .understand-anything/, not .ua/ — the task brief's assumption about the current default was outdated. Used the real default.
• Plugin marketplace source is Lum1104/Understand-Anything, not Egonex-AI/Understand-Anything as cited in the task — likely a fork/rename; already installed and enabled at user scope so no /plugin marketplace add was needed.
• Ran only the core /understand pipeline (scan → file-analyzer batches → assemble-reviewer → architecture-analyzer → tour-builder → inline validation → save), per instructions — no /understand-domain, /understand-knowledge, /understand-onboard, or dashboard server left running.
• One known graph gap, left unfixed per the assemble-reviewer's judgment: 3 front-end JS classes (ClickTrailConsent, ClickTrailAttribution, ClickTrailEvents) are missing per-method function nodes because the bundled tree-sitter extractor doesn't descend into their outer IIFE wrapper — everything else (all PHP classes/functions, PHP traits via a separate workaround) extracted cleanly.

Test plan

• Validated knowledge-graph.json is well-formed JSON with non-trivial node count
• Ran the tool's own inline deterministic validator — 0 issues, 52 orphan-node warnings (expected for isolated helpers)
• Confirmed .understand-anything/ excluded from .distignore
• Confirmed file size (592 KB) is well under the 10 MB git-lfs threshold — no LFS setup needed
• Open /understand-dashboard locally to browse the graph (not run as part of this PR — no need to leave a server process running)