refactor: remove sample_pose_cache module and streamline pose processing in pipeline

feat(coach): disable verifier by default

feat: load external coach knowledge packs

feat(pipeline): implement sample pose caching and enhance upload handling

Implement grounded coach summary with HF SLM

Refactor(pipeline): improve code readability and update function calls for clarity

Merge branch 'main' into NLag/issue4

feat(report): stream analysis progress

feat(report): add annotated issue clips

Merge branch 'main' into NLag/issue4

refactor(exercises): route pipeline through exercise objects

Implement frame-level issue markers

Merge branch 'main' into NLag/issue4

Implement exercise classifier router

Surface rep metrics in the app

refactor(ui): clarify mocked downstream analysis

feat(renderer): generate annotated pose videos

feat(pipeline): persist rep debug artifacts

feat(pose): add pluggable pose backends

feat(pipeline): harden mock artifact contracts

first commit