The Copilot content converter only replaced `~/.claude/` and
`$HOME/.claude/` when followed by a literal `/`. Bare references
(e.g. `configDir = ~/.claude` at end of line) slipped through and
triggered the post-install "Found N unreplaced .claude path reference(s)"
warning, since the leak scanner uses `(?:~|$HOME)/\.claude\b`.
Switched both replacements to a `(\/|\b)` capture group so trailing-slash
and bare forms are handled in a single pass — matching the pattern
already used by Antigravity, OpenCode, Kilo, and Codex converters.
Closes#2545