fix: CI workflow - add setup steps, split test jobs, add coverage upload

[sam1064max]

Description

Fixes CI workflow failing due to missing setup steps and incorrect job configuration.

Changes

• Added actions/setup-python@v5 (Python 3.12) to all Python jobs
• Added actions/setup-node@v4 (Node 20) to lint job
• Added pip cache for backend and analytics dependencies
• Added npm cache for frontend dependencies
• Split monolithic test job into test-backend and test-analytics for parallelism
• Installed backend and analytics requirements.txt before lint/test
• Used npm ci instead of ad-hoc npm install eslint
• Replaced inline docker build with docker/build-push-action@v5 (Buildx caching)
• Added coverage artifact upload via actions/upload-artifact@v4
• Updated release job to softprops/action-gh-release@v2 with auto release notes
• Removed npm test (no test script in frontend package.json; typecheck covers validation)
• Scoped push/PR triggers to main and develop only

Closes #1

[sam1064max]

Code Review: CI Workflow Fix

lint job L90: 🔴 bug: tests import from \�pp.xxx\ which is under \�ackend/app/. Running \pytest backend/tests/\ from repo root won't resolve \�pp\ module. Add \PYTHONPATH=backend\ or use \working-directory: backend.

** est-analytics job L110:** 🔴 bug: same module resolution issue. Analytics tests import from \�pp.path_analyzer\ which is under \�nalytics/app/. Use \working-directory: analytics\ or set \PYTHONPATH=analytics.

lint job L87: 🟡 risk:
pm ci\ requires \package-lock.json\ which may not be committed. If lock file missing,
pm ci\ fails. Use
pm install\ as fallback or verify lock file exists.

lint job L93: 🔵 nit:
uff check\ only lints, doesn't enforce formatting. Add
uff format --check backend/ analytics/\ before lint step.

** est-backend job L105:** 🔵 nit: \coverage.xml\ path ambiguous. pytest generates it in CWD. Since no \working-directory, it lands at repo root. Upload artifact path should match. Confirmed OK as-is since both use root.

�uild job L128: 🔵 nit: build jobs depend on lint+test but no caching across jobs. \setup-python\ cache helps pip, but full dependency install runs on every test job. Acceptable for POC, consider composite actions in future.

Summary

Two critical bugs (import path resolution), one risk (npm ci), two nits. Fix import paths and the rest LGTM.