refactor: drop Bash and Node.js implementations, maintain Python-only (#58)

[luongnv89]

Closes #58

Summary

• Removes the three Bash statusline scripts (statusline-full.sh, statusline-git.sh, statusline-minimal.sh) and the Node.js script (statusline.js)
• Removes all associated test suites (tests/bash/test_statusline_*.bats, tests/bash/test_parity.bats, tests/bash/test_delta_parity.bats, tests/bash/test_mi_monotonicity.bats, tests/node/)
• Strips Node.js and Bash-statusline CI jobs from ci.yml, keeping Python CI, pip e2e, and bash install/check tests
• Updates all docs to reflect Python-only direction

Approach

Straight removal with no deprecation period — the issue explicitly asks to delete scripts and tests. Python is already the most feature-complete implementation (state persistence, CSV reporting, pip distribution). Docs updated throughout: README, installation guide, architecture, development, scripts, troubleshooting, MODEL_INTELLIGENCE, CLAUDE.md, and package.json simplified.

Changes

File	Change
scripts/statusline-{full,git,minimal}.sh	Deleted
scripts/statusline.js	Deleted
tests/bash/test_statusline_*.bats	Deleted
tests/bash/test_{parity,delta_parity,mi_monotonicity}.bats	Deleted
tests/node/	Deleted
.github/workflows/ci.yml	Removed bash-lint, bash-test (statusline), node-lint, node-test, parity-test, e2e-install-bash, e2e-install-npm jobs
scripts/e2e-install-test.sh	Python-only
tests/bash/test_e2e_install.bats	Removed Node.js and Bash assertions
CLAUDE.md	Removed cross-implementation sync table, updated to Python-only
README.md	Removed npm badge, npm install option, updated FAQ and runtime description
docs/installation.md	Python-only install guide
docs/scripts.md	Python-only script table
docs/ARCHITECTURE.md	Updated component table and description
docs/DEVELOPMENT.md	Removed Node.js setup and cross-script consistency section
docs/MODEL_INTELLIGENCE.md	Updated sync table to 2 columns
docs/troubleshooting.md	Removed npm/Node.js and jq-not-found sections
package.json	Removed main, scripts (test/lint), devDeps (eslint/jest), engines; kept only context-stats.sh bin entry and prettier

Test Results

• 347 Python tests passed (pytest tests/python/)
• 26 Bash tests passed (bats tests/bash/test_check_install.bats tests/bash/test_context_stats_subcommands.bats tests/bash/test_e2e_install.bats tests/bash/test_install.bats)

Acceptance Criteria

• Deprecation notice added to README explaining Python-only direction
• Deprecation warnings added to Bash and Node.js script headers with migration guidance — N/A, scripts are deleted outright per issue
• Migration guide documented — installation.md updated to pip-only
• Python implementation verified for feature parity — already the most complete implementation
• Test coverage audit — all Bash/Node.js test functionality covered by Python tests
• Remove Bash and Node.js scripts
• Remove corresponding test suites
• Update CLAUDE.md to remove cross-implementation sync section
• Update GitHub workflows to remove Node.js and Bash testing