feat: refactor app-sidecar integration and modularize reasoning pipeline

[adgk2349]

Summary

This PR splits and lands a large refactor across the macOS app layer and the sidecar reasoning pipeline.

It introduces plugin panel and streaming tag handling improvements in the app, and modularizes sidecar reasoning/memory/web execution paths for better maintainability and control flow clarity.

Changes

• App (SwiftUI/macOS)

• Refactored sidecar bootstrap/process/client integration paths

• Added plugin panel view-model/view host flow

• Improved chat flow, workspace, persistence, and settings panel wiring

• Added stream tag parsing and markdown rendering updates

• Added language support metadata updates and language docs file

• Sidecar (Python)

• Modularized reasoning pipeline into dedicated strategy/helper modules

• Split DB/model manager concerns into dedicated module packages

• Added recall/web gate and execution helper layers

• Added isolated MLX worker and parser/runtime cleanup

• Extended memory committer/retrieval paths and related strategy routing

• Tests/Scripts

• Updated existing sanitize/memory/v2 tests to match refactor

• Added memory committer regenerate-skip test

• Added sidecar utility scripts for memory longevity and stream turn reporting

Commits

1. 1754e67 feat(app): refactor sidecar integration and plugin panel flows
2. 38a021e feat(sidecar): modularize reasoning pipeline and memory/web flows

Validation

• Ran targeted Python test suite:
• pytest -q sidecar/tests/test_local_inference_sanitize_conversation.py sidecar/tests/test_local_inference_sanitize_runtime.py sidecar/tests/test_local_inference_sanitize_sanitize.py sidecar/tests/test_memory_service_digest.py
• Result: 84 passed

Notes

• This branch intentionally excludes local temp artifacts, logs, and benchmark output files from commit scope.
• PR is ready for review; merge was intentionally not performed.