Default registrants to active; show counts and event date

[maebeale]

What is the goal of this PR and why is this important?

• Admins managing an event need to focus on registrants who are actually attending, not those who cancelled or no-showed.
• Previously the registrants list showed every registrant regardless of status, burying the active roster.
• This defaults the page to the active filter, surfaces both active and inactive counts so admins can switch at a glance, and adds at-a-glance context (active count in the heading + the event's date) so admins don't have to bounce back to the dashboard. It also tightens the table layout and polishes some microcopy.

How did you approach the change?

Active/inactive filtering

• Added an inactive scope to EventRegistration (mirrors the existing active scope; reuses INACTIVE_STATUSES = cancelled, no_show).
• EventsController#registrants now computes @active_count / @inactive_count from the filtered base scope (so counts reflect the current search/filters) and defaults to the active filter when no status_filter param is given.
• An explicit attendance_status selection still takes precedence over the active/inactive grouping, preserving the dashboard drill-down behavior.
• Two-tab segmented control (Active (N) / Inactive (M)) in the results header; tabs do a full-page nav so the search form's hidden status_filter field stays in sync.

Page context

• Heading now shows the active count — Registrants (N) — and the event's date_range (the same decorator method the dashboard uses) appears beside the title.

Table layout & copy polish

• Shortened column headers (Organization(s) → Organization, Payment status → Payment, Attendance status → Attendance) and relabeled the column toggle to "User confirmation".
• Gave the Organization column the flexible width (w-full) and raised its truncation so org names are readable; trimmed the oversized Name column to compensate.
• Each organization name now links to its profile (organization_path).
• Kept payment badges on one line (whitespace-nowrap) so "$N due" doesn't wrap.
• Centered the status columns (Scholarship / Payment / Attendance) — header and pill together — so they read as a distinct status band between the left-aligned text columns and the right-aligned Edit action.
• Reworded the comment hint "Reason you're making a note" → "Reason for this note".

UI Testing Checklist

• Registrants page loads with the Active tab selected by default, showing only active registrants
• Heading shows Registrants (N) with the active count, plus event title + date range
• Active/inactive counts are accurate and update with search/filters
• Clicking Inactive shows only cancelled/no-show registrants; an explicit attendance status still wins
• Organization column is roomy, names link to the org profile, payment badges don't wrap
• Status column headers and pills are centered together

Anything else to add?

• Rebased onto main, which renamed the manage action/route/partials to registrants and split the dev seeds into db/seeds/dev/*; conflicts resolved to keep both main's new filters and this branch's active/inactive logic.
• Request specs cover: counts rendering, the active default, the inactive filter, attendance_status precedence, the heading count, and the event date.
• date_range is weekday-prefixed (e.g. "Tue, Jun 2, 2026") to match the dashboard; flagging in case a bare date is preferred.

🤖 Generated with Claude Code

[maebeale]

Counts are computed from the keyword-filtered scope before the active/inactive grouping is applied, so both tab counts always reflect the current search rather than only the visible tab.

[maebeale]

An explicit attendance_status takes precedence over the active/inactive default, preserving the existing dropdown drill-down. Absent that param, we default to the active filter.

[maebeale]

Tabs use turbo_frame: "_top" (full-page nav) intentionally: the search form lives outside the manage_results frame, so a frame-only swap would leave the form's hidden status_filter stale and out of sync with the visible tab.

[maebeale]

Hidden field keeps the selected tab when the keyword/status search form is submitted (which updates only the results frame).