feat(tri): Kaggle CLI for DeepMind AGI Hackathon

[gHashTag]

Implement unified CLI for Kaggle operations as part of the DeepMind AGI Hackathon competition.

Commands:

• tri kaggle auth — Check ~/.kaggle/kaggle.json
• tri kaggle meta [track] — Generate kernel-metadata.json
• tri kaggle push — Push notebooks to Kaggle
• tri kaggle status — Check kernel status
• tri kaggle validate — Validate submission format

Tracks:

• track1_learning (10 notebooks, THLP)
• track2_metacognition (2 notebooks, TMP) ← PILOT
• track3_attention (10 notebooks, TAGP)
• track4_executive (10 notebooks, TEFB)
• track5_social (8 notebooks, TSCP)

Reference: .claude/plans/mutable-stirring-russell.md

[gHashTag]

Fully implemented in src/tri/tri_kaggle.zig (863 LOC). All 5 commands wired: tri kaggle {auth|meta|push|status|validate}. All 5 tracks supported (track1-5). CLI routing in src/tri/main.zig:911.