feat: sync last-semester IPK with graduation input and auto-update status (ENH-006)

[ffooll-bit]

Summary

Sync the student's "last semester IPK" as a single, two-way synced source shared between the step 5 graduation IPK input and the last (newest) academic row in the step 2 table. When the last academic row is still active and its IPK differs from the Excel IPK, an "Auto-update IPK & status ke Aktif" button stages the Excel IPK and the Aktif status for that row; when the row is inactive, only an informational warning is shown. The staged value flows through the existing stepPost → finish() deferred push, so no mutation happens until submission.

Related issues

Fixes #100

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): 36/36
• 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)

Not attached (no Neo Feeder mutation; wizard session cancelled before advancing).

Notes for reviewers

• The Auto-update button resolves the "Aktif" status code from the existing status dropdown options ($statusOptions, label match) instead of hardcoding 'A' — consistent with the design decision that the table's own input is the source of truth for status.
• No controller change to finish()/stepPost(): the synced IPK and status are captured normally on stepPost and pushed by the existing per-semester updatePerkuliahanMahasiswa loop at finish().
• Browser-verified live: Excel IPK 3.5 vs last-row PDDIKTI IPK 3.40 (semester 20252, active) triggered the banner + button; typing in step 5 synced to the table and vice-versa; the button set the last-row IPK to the Excel value, selected status Aktif, synced step 5, and removed the banner. Inactive last rows render only the warning.