Add Sweep Pipe Network example with legend and FPS monitor

[aka-blackboots]

Motivation

• Provide a realistic routing demo that combines the existing Sweep path+profile API with contextual walls and visualization controls to demonstrate multi-pipe networks.
• Surface per-pipe metadata and a small UI (legend + outline toggle) so users can inspect pipe types and quickly verify which profiles were used.
• Add lightweight runtime diagnostics (Three.js Stats FPS panel) to help evaluate performance for different scene configurations.

Description

• Added a new example page main/opengeometry-three/examples-vite/operations/sweep-pipe-network.html that builds a building-scale routed pipe network using Sweep with explicit path and profile, cuboid walls, an outlines toggle, a pipe legend, and a console-printed network config.
• Registered the new example in main/opengeometry-three/examples-vite/index.html (added an index card and incremented the operations count to 9 items).
• Added an AI handoff note at AI-DOCS/2026-03-11-sweep-pipe-network-example.md documenting what changed, why, how to run locally, and known caveats.
• The example includes four pipe types (Supply Air, Return Air, Chilled Water, Drain) with distinct colors, profile dimensions and caps, draws dashed path lines, exposes an outlines toggle that updates both sweeps and walls, and integrates Three.js Stats for FPS display.

Testing

• Ran npm --prefix main/opengeometry-three run build-example-three, which failed in this environment due to missing wasm bindings at main/opengeometry/pkg/opengeometry_bg.wasm (import resolution error noted).
• Started the dev server with npm --prefix main/opengeometry-three run dev-example-three, which reported the same missing wasm import errors for runtime modules although the server started; this prevented a full in-browser render without the wasm assets.
• Performed a headless page access and captured a screenshot via Playwright to validate page load mechanics (screenshot artifact produced: artifacts/sweep-pipe-network.png) despite import resolution warnings.

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Codex Task