Generalize BMS cell data model for arbitrary cell counts

[bracyw]

Changes

Replaces all hardcoded BMS cell-count enums and fixed-length tuple types with a single config-driven BMS_CONFIG object (in new bms.config.ts file). To support a different accumulator with different cell/segment counts, only the values in BMS_CONFIG need to change — everything else derives from it.

The refactoring:

• Extracted BMS_CONFIG into its own file to break a circular import between bms.utils.ts ↔ topic.utils.ts (old const enums were inlined at compile time; new runtime object needed independent module)
• Changed Segment enum to type alias with dynamically generated allSegments array
• Replaced all cell-index enums with Array.from() calls derived from BMS_CONFIG
• Replaced fixed tuple types with CellReading[] and CellReading[][]
• Replaced hardcoded values (e.g., beta cell cap of 10) with config references

Files changed: bms.config.ts (new), bms.utils.ts, topic.utils.ts, cell.service.ts, cell-by-cell-heat-map.component.ts

Test Cases

• App loads without console errors at /bms
• All 5 segments render with temperature, voltage, and chip temp summaries
• Cell-by-cell heat maps display correct cell counts (14 alpha, 11 beta per segment)
• Segment detail view (/bms/segment/:id) navigates and renders correctly
• ng build succeeds with no new warnings

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Closes #525