Cycle 21: Support Groups, Urban Detox AI Coach, and Mindfulness Content

[mx57]

Cycle 21 development for the Sober Path application:

1. Introduced curated Support Groups inside Community tab with dynamic joining, local persistence, +20 Karma reward, and Haptic feedback.
2. Built the 'Осознанность в мегаполисе' mindfulness micro-course and expanded the knowledge database with 11 advanced articles.
3. Created the 5-step interactive 'Urban Detox' stress relief exercise in the AI Coach triggered by urban keywords, prioritizing exercises over general reframing and referencing user's groups.
4. Added full unit test coverage and ran web automation tests with captured visual proofs.
5. Upgraded version bump to 1.21.0, drafted release notes, and updated task tracking.

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PR created automatically by Jules for task 1636558805791485685 started by @mx57

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