Treat uppercase M as mega when grouping component values

[DominikPalo]

units.compMatch (used by componentValue to build the BOM grouping key for the Value column) lowercased the whole value before parsing. A single-letter M prefix was therefore always read as milli, since PREFIX_MILLI contains "m" and PREFIX_MEGA only has "mega"/"meg".

As a result, a 1 MΩ resistor and a 1 mΩ current-sense shunt with the same footprint were grouped into one BOM row, and the row was labelled with the first part's value (e.g. "1M"). Values like 4M7 (4.7 MΩ) or 2.2MΩ were also treated as milli.

This change still matches case-insensitively, but when the parsed prefix is the single letter m it checks the original character: uppercase M resolves to mega. Nothing else changes: Meg/MEG/mega, all other prefixes, the 4M7 style and the decimal/thousands separator handling behave as before.

Testing

componentValue() on master vs this branch:

Value	master	this PR
1M, 1MOhm (R)	0.001 R	1e6 R
4M7 (R)	0.0047 R	4.7e6 R
2.2MΩ (R)	0.0022 R	2.2e6 R
10M (C)	0.01 F	1e7 F
1m, 1mR, 1mOhm, 4m7, 2.2mΩ, 10mH	milli	milli (unchanged)
1Meg, 1MEG, 1meg, 1mega, 4k7, 4K7, 0R1, 100n, 1,000		unchanged

End to end, an Eagle test board with three parts in the same package with values 1M, 1m and 1MOhm:

• master: one BOM row [R1, R2, R3], all shown as "1M"
• this PR: [R1, R3] ("1M") and [R2] ("1m")

Note: this follows the SI prefix letter strictly, so a value like 10M on a capacitor now parses as megafarads rather than millifarads. Neither is a realistic capacitor value. Legacy notations like 10MFD for microfarads were not recognized before and still aren't.

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