Settings env values are now tracked, with groundwork to withhold them from some sources

What

Settings files can set environment variables, the named values programs read at startup, through an env block. This release changes how those are handled.

• The env manager now keeps a record of every env value offered by settings, keyed by the upper-cased variable name, and adds isSettingsSourcedEnvValue so later checks can tell whether a variable's current value came from settings. The record is cleared when settings are reset.
• filterSettingsEnv now returns nothing for a settings source when withholdsEnvFrom(source) is true, and processWrapper goes through the same check instead of being read directly from each source. In this build the switch that would turn this on always returns false, so nothing is withheld yet.
• Claude Code now warns when env keys meant for spawning host processes are dropped.
• Settings are reset if the path of the user settings file moves while settings are being applied.

Why

For now this changes nothing you can see beyond the new warning. The members suggest it prepares for a mode where project or user settings cannot redirect environment variables for a pinned login.