- Group timesheet descriptions by first line (heading) to avoid
  repetition when multiple entries share the same category
- Replace `->` with arrow symbol and render bullet/arrow lines smaller
- Set invoice due date to posting date + 14 days by default
- Only show "(bis zum ...)" on invoice when due date is in the future
- Fix PartnerCapitalDashboard: use __(msg, args) instead of deprecated .format()

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

format_currency() returns HTML with a div wrapper; escape_html then
renders it as literal text. Strip HTML tags first to get plain text.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

- Add checkbox "Kompakte Rechnung mit Anhang" on Sales Invoice
- Add custom_performed_by field on Sales Invoice Timesheet child table
- Store performed_by on timesheet rows at invoice creation
- Compact mode: main invoice shows summary grouped by (activity type,
  performer) with aggregated hours and totals
- Compact mode: separate attachment page with all individual timesheet
  entries (date, activity, performer, description, hours — no times)
- Normal mode: unchanged detailed layout

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frappe.utils.strip_html is not available in this Frappe version.
Use $("<div>").html(...).text() instead, which works universally.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Only warn about late GL entries in the most recent allocation period.
Entries in older periods are by definition already covered by a
subsequent sequential allocation, so the warning was spurious there.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>