Follow-up to the salvaged hermes_constants expansion (#109212): the CLI has
~30 raw `os.environ["HERMES_HOME"]` readers (fast --version path, early
display.interface probe, profile re-home, dotenv loader, subprocess-home
helper) that never go through get_hermes_home(). A literal `~` (fish, or
any quoted value) left them resolving `~/.hermes` against cwd while the
resolver now expands it, so the process would disagree with itself.
Normalize the env var once, at the earliest point of hermes_cli/main.py
(stdlib-only, before the fast paths), and expand it in the one raw
hermes_constants reader (`_profile_home_path`). A relative value that is
not tilde/variable-shaped is deliberately left alone: rejecting it would
break `HERMES_HOME=./tmp-home` in tests and CI for no user-facing gain.
Tests: real-CLI subprocess with HERMES_HOME='~/.x' under a fake HOME asserts
`config path` lands in the fake home and that no literal `~` directory
appears under cwd (the reporter's acceptance criterion, #114353), plus a
unit test for the normalizer. Docs: environment-variables reference.
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