[Bug] Resumed sessions ignore [1m] context spec again (regression, previously fixed in #60548)

Description

Same bug as #60548: resumed sessions ignore the [1m] context window suffix in the model setting and fall back to 200k context. Fresh sessions work correctly.

This was fixed in v2.1.149 but has reappeared somewhere between v2.1.150 and v2.1.160.

Repro

1. Set "model": "claude-opus-4-6[1m]" in ~/.claude/settings.json
2. Start a fresh session - /context shows 1M (correct)
3. Exit and resume the session - /context shows 200k (wrong)

Previous fix

#60548 - originally broken in v2.1.144, fixed in v2.1.149.

Environment

• macOS, standalone installer
• claude-opus-4-6[1m] in global settings.json