perf: tighten viewer runtime ownership

[Aymericr]

What does this PR do?

Tightens viewer lifecycle and per-frame work without changing the default animation schedule:

• recursively disposes nested geometry-build resources while preserving cached materials
• pauses the mounted 3D viewer after hidden 2D-mode initialization completes
• indexes cabinet flame objects instead of traversing every cabinet subtree each frame
• reports performance timing from the supplied R3F delta rather than mutating the shared clock

Maintainer follow-ups:

• fixed the cabinet flame loop so a throttled flame jet skips only its own update rather than aborting later pulse/material animation
• rebased after perf(viewer): sew a level's walls into one mesh #608 and feat(viewer): make the render-loop frame cap configurable via maxFps #671, preserving the public maxFps API and its monotonic frame clock while composing renderPaused into the same limiter

Validation

• bun run check: 1,670 files clean
• bun run check-types: 10/10 tasks
• bun run build: 8/8 tasks
• focused core/viewer/nodes suite: 1,089 passed, 1 skipped, 0 failed
• browser smoke on the contributed 1,089-wall fixture: DIRTY 0, six meshes, clean 3D → 2D → 3D transitions, no runtime errors
• public/private boundary scan: only public editor/core/viewer/nodes code; no auth, environment, hosted-community, project identifiers, or private URLs

Screenshots / screen recording

N/A — lifecycle, disposal, frame-loop, and animation-internal changes; no intentional UI change.

Checklist

• I have tested this locally with the standalone editor
• My code follows the existing code style
• Relevant architecture contracts remain documented
• This PR targets the main branch

Full demand rendering and shadow dirty-gating remain measurement-gated by the active runtime-performance plan.

---

Note

Medium Risk
Changes affect the global render loop, geometry disposal, and per-frame cabinet animation; behavior is mostly performance and leak fixes, but incorrect pause/disposal could cause stale visuals or rare GPU resource issues.

Overview
Viewer runtime gains a host-controlled renderPaused prop wired through FrameLimiter so the WebGL context stays mounted but scene frames stop advancing. The editor sets this when the 3D pane is hidden and loading has finished (!show3d && !showLoader), cutting per-frame work in 2D-only mode.

Resource lifecycle introduces disposeObject3DResources to walk a subtree, dedupe geometry/material disposal, and skip materials tagged __pascalCachedMaterial. Geometry rebuilds use it instead of inline disposal; MEP preview ghosts dispose replaced materials when ghostifying and tear down the whole ghost on unmount.

Cabinet flame animation pre-collects flame objects per cabinet (rebuilt when the root or child list changes) instead of traversing every cabinet subtree each frame. animateCabinetFlames now iterates that list and uses continue instead of return, so a throttled flame-jet skip no longer stops pulse/material animation for later flames (covered by new tests).

Perf overlay frame timing reads the useFrame delta argument instead of calling clock.getDelta(), avoiding extra mutation of the shared clock.

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[Aymericr]

Maintainer follow-up pushed in d455adf3.

The indexed cabinet-flame loop retained traversal-era return statements. A throttled flame jet could therefore abort animation for every later indexed flame. Those exits are now per-flame continue statements, with a regression covering a throttled jet followed by a pulse.

Validated:

• bun run check
• full bun run check-types (10/10 tasks)
• cabinet suite (274 passed)
• GitHub CI and Bugbot green

The remaining merge gate is the maintainer's local 2D/3D and cabinet-animation smoke.

[Aymericr]

Final maintainer gate is complete after rebasing onto #608 and #671.

The overlap composes the two contracts rather than choosing one: FrameLimiter receives maxFps and renderPaused, retains the monotonic synthetic clock across limiter restarts, and keeps the mounted renderer warm while hidden 2D mode stops scene advancement.

Validation on this exact head: Biome checked 1,670 files; 10/10 type tasks passed; 8/8 build tasks passed; 1,089 focused tests passed with one existing skip; the 1,089-wall browser fixture reached DIRTY 0 and six meshes, and switched 3D/2D/3D without runtime errors. The final diff remains entirely in the public editor packages and contains no hosted-community, auth, environment, project, or private-repository material. Remote quality, CLI smoke, and Bugbot are green.