Release v0.1.2

• cfcc580 Add CHANGELOG.md (Keep a Changelog format)
• dd290bf Advise readers to inspect get-ivim.sh before piping to bash
• f8d0cad Expand .gitignore to cover common contributor footguns
• b99b0ca Un-export _IVIM_TERMINAL_SOURCED recursion guard
• 2969212 Resolve git's absolute path before sourcing user init files
• 54eb721 Roll back backups on interrupted install
• 0ac397b Harden backup restore against TOCTOU attack
• 9091ed8 Exit insert mode on entering non-modifiable buffer
• 091275e Fix broken color escapes in get-ivim.sh info/ok/warn/err
• c297a29 Fire keyword completion once per word, not per keystroke
• b16af9b Fix Rust/Lua/C++ autocomplete freeze on :: and similar