* fix(imessage): detect MiniMax mm: namespaced reasoning tags in reflection guard
The iMessage reflection guard's THINKING_TAG_RE only matched bare
`<think>/<thought>` tags, so MiniMax's `<mm:think>` namespaced reasoning
tags (and Anthropic's `antml:` prefix) were not recognized as reflected
assistant content. When such reasoning leaked back inbound, the guard
treated it as a normal user message instead of dropping it, allowing
recursive echo amplification.
Accept the known reasoning-tag namespace prefixes `(?:antml:|mm:)?` on
the think/thought alternatives, mirroring the shared reasoning-tag
contract in src/shared/text/reasoning-tags.ts (PR #93767). This is the
remaining channel-monitor complement of #93767 for the iMessage path;
the optional prefix is a pure recognition enhancement with no change to
the bare-tag, code-region exemption, or other reflection patterns.
Verified by driving the real detectReflectedContent export:
<mm:think>secret</mm:think>visible -> isReflection=true (was false)
<think>...</think> -> isReflection=true
<think>secret</think> -> isReflection=true (no regression)
"thinking about minimax algorithms" -> isReflection=false (no false-positive)
`<mm:think>x</mm:think>` in code -> isReflection=false (code exemption kept)
* chore: retrigger CI for real behavior proof check
* refactor(imessage): tighten reflection guard coverage
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Co-authored-by: Peter Steinberger <steipete@golden-gate.local>
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