[Feat] Add <fresh-session> tag to skip context injection

[kamil-hassan201]

Add <fresh-session> tag to skip context injection

Summary

Adds a <fresh-session> tag that allows starting a session without loading any historical context (no observations, summaries, or timeline).

Default behavior is unchanged; this is an explicit, per-session opt-in.

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Usage

<fresh-session>
Review this code for security issues.

The tag is detected only in the first user message and is stripped before storage.

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Changes

• context-hook.ts – Skip context injection when <fresh-session> is present
• tag-stripping.ts – Remove tag from stored messages
• fresh-session.test.ts – 11 tests added (all passing)
• fresh-session.mdx – User documentation

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Why

• Enables unbiased reviews and unrelated tasks
• Provides explicit per-session control without global flags

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Testing

npm test -- tests/happy-paths/fresh-session.test.ts

✓ 11 tests passing

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Compatibility

✅ Fully backward compatible