Enforce the rule where it is declared

Each agent adapter in context-bridge declares the CLI flags that would break a resumed session — seven for Grok, four for Antigravity. Declaring them was the easy part.

The filter that dropped those flags read from its own list somewhere else in the codebase. Two sources for one fact, and only one of them was updated when an adapter changed. The declarations were right, the enforcement was stale, and nothing complained: the flags were still listed, still documented, still wrong.

The filter now reads each adapter's own conflictFlags, with a test proving the flag an agent declares is the flag that gets dropped. A rule enforced somewhere other than where it is declared is not a rule, it is a copy — and copies drift silently, because nothing is watching the gap between them.