v0.1.2

Fixes two bugs that a user hits on their first real project.

• Device names are now spelled the way GX Works3 spells them. X, Y, B and W are numbered in hexadecimal; the index, xref and query paths were reporting them in decimal, so query-device, query-comment, where-used and trace-device named devices that do not exist in the customer's project. Devices whose hex number contains A-F were rejected outright as "invalid device". (#16, #17)
• trace-device --strict-logic no longer answers FALSE for a rung with a b-contact on a hex-numbered device — it was claiming an output could never turn on. (#18)

Also adds synthetic-project --profile demo-line: a fictional 14-station transfer line of about 500 rungs, so the tool can be evaluated and bugs reproduced without sharing a real project. (#15)

Existing .gx3_index databases are refused with a message naming the rebuild command, rather than silently missing every lookup.