perf: server-side aggregate sensors and client-side optimizations

[flatline-84]

Summary

Linus Dashboard is great but I find that my tablet struggles with it. Part of it is all my devices, part of it is the tablet is not very good. Hoping to make LD a little quicker. Also did some dev changes since it was hard to get this repo initialized and ready to work in.

• New sensor platform creates server-side aggregate sensors per domain/floor, reducing home view template evaluations from ~60 to ~3
• Fix several client-side bottlenecks: O(n²) sorts, sequential area card creation, redundant template computations, and forced per-minute re-evaluations

Changes

Server-side aggregate sensors

• aggregate.py: constants and pure computation functions (active states, icons, colors)
• sensor.py: diagnostic sensors, event-driven with 100ms debounce, hidden from default UI
• Sensors cover global and floor scope; area scope stays client-side

Frontend

• AggregateChip uses server-side sensor when available (state_attr(...) instead of inlining 100 entity IDs), falls back gracefully if sensor doesn't exist
• Removed now() from getLastChangedTemplate — was forcing all relative_time() cards to re-evaluate every minute
• Parallelized HomeView area card creation with Promise.all()
• Fixed O(n² log n) sort — replaced indexOf() in comparator with pre-built Map
• Replaced exposedDomainIds.some(...) inner-loop calls with a pre-computed Set
• Replaced Object.keys(DEVICE_CLASSES).includes() with a module-level Set
• Added explicit entity_id arrays to AggregateChip and UnavailableChip for faster Mushroom subscriptions

Performance

Metric	Before	After
Template evaluations per state change	~60	~3
Jinja2 template size per chip	~2–10KB	~80 bytes
WebSocket subscriptions	~2000	~20

Test plan

Uh there was no real test plan. I put it in my personal HA with ~2000 entities / ~135 devices and it seemed a little faster? Probably a bit of placebo but I expect this to be a first pass for performance improves

[flatline-84]

Not sure what this folder is for?

[flatline-84]

Errors booting HA up if these are enabled, since the files don't exist

[flatline-84]

This allows LD to be present as an integration in the new HA setup