Prune CONTEXT.md glossary to genuinely ambiguous terms

Idea

CONTEXT.md's glossary has drifted from its purpose. It should pin ubiquitous language where ambiguity has actually caused (or would plausibly cause) confusion — instead the BMS cell voltages section (C-ADC voltage, S-ADC voltage, CvS) reads as per-topic reference documentation: topic shapes, units, and which heatmap view renders each. None of that is ambiguous; the code and the Odyssey defs already say it, and it goes stale as topics evolve (the S Volts entry already needed an Expected-to-confirmed correction in #712).

Proposed pass

Review every glossary entry against one test: does this term have two plausible meanings, or a collision, that has bitten or would bite a reader? Keep those (e.g. the C Volts vs S Volts naming split arguably qualifies since "the voltage" became ambiguous). Trim entries that merely restate topic strings and view names, or compress them to the single disambiguating sentence. Also check the Avoid lines still earn their place.

Context

Raised 2026-07-15 while deciding whether the new per-cell Open Wire flag (#711) deserved an entry — the disambiguation vs the pack-level Critical Open_Wire fault was the only defensible part, and even that was judged not worth the bloat. Good candidate for an AI pass with human review of the diff.