docs: update README with current project state and Neo Feeder API endpoints (DOC-002)

[ffooll-bit]

Summary

Updates README.md to reflect the current project state and records the Neo Feeder API endpoints the project consumes:

• Development Status now lists the active features (Login/Auth, AdminLTE 4, Profil PT, Mahasiswa, Aktivitas Kuliah, Mahasiswa Lulus/DO, PISN Graduation wizard, Verifikasi IPK).
• Directory Structure updated with the actual Controllers/Libraries/Views.
• Neo Feeder API section expanded: request/response envelope, List/Get endpoints table, Mutation endpoints table (with key and the complete-record requirement), the two cloud REST transcript endpoints, and a dedicated GetDictionary schema-inspection subsection.

Related issues

Fixes #120

Checklist

• php -l passes on all modified PHP files
• npm run build succeeds and committed assets are up to date
• php spark routes shows correct new routes (if routes changed)
• vendor/bin/php-cs-fixer fix passes (no style violations)
• vendor/bin/phpunit is green (if tests exist)
• No debug code: dd(), var_dump(), console.log(), print_r(), exit()
• All user inputs validated server-side
• All POST forms include csrf_field()
• All HTML output uses esc()
• No unrelated files changed
• CHANGELOG updated if this is a user-facing change
• Behaviour verified in the browser if UI changed (attach a screenshot if useful)

Screenshot (if applicable)

N/A — documentation-only change.

Notes for reviewers

Markdown-only change: README.md (+110/-9) plus the tracker docs/IMPROVEMENTS.md (DOC-002 → implemented). No user-facing behaviour change, so no CHANGELOG entry. Markdown verified LF-only + no-BOM (CI markdown checks pass).