Manage billing from the control panel

A Billing tab (tiers, their dated prices, and everything we are owed), a billing
panel on each club (plan, periods, payment history, invoice), and the dues on the
dashboard and the club tables.

Every state change goes through the billing service, and a BillingError surfaces
as a message rather than a 500 -- so "that period is waived", "no price in force",
"already billed for that period" and a missing PDF library all explain themselves
instead of crashing.

The dashboard now separates the two pots of money that were previously one word.
"Revenue per month" was CLUB SHOP revenue -- members paying their clubs, which is
never ours -- sitting on our dashboard under a label that implied it was income.
It is now "Platform dues per month" (what clubs paid us) with the club-shop series
renamed club_revenue, and the club tables carry a Plan column and what each club
owes us, annotated in the same single query.

Rate changes are add-only in the UI as well as the model: the price form creates a
dated row and never edits the last one, and a test asserts that raising the rate
leaves an already-open period at the amount it was billed at.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

static/css/app.css

@@ -3195,6 +3195,9 @@
   .hidden {
     display: none;
   }
+  .inline {
+    display: inline;
+  }
   .inline-block {
     display: inline-block;
   }
@@ -3558,6 +3561,9 @@
   .pb-2 {
     padding-bottom: calc(var(--spacing) * 2);
   }
+  .pl-8 {
+    padding-left: calc(var(--spacing) * 8);
+  }
   .text-center {
     text-align: center;
   }
@@ -3839,6 +3845,12 @@
       --badge-fg: var(--color-error-content);
     }
   }
+  .badge-info {
+    @layer daisyui.l1.l2 {
+      --badge-color: var(--color-info);
+      --badge-fg: var(--color-info-content);
+    }
+  }
   .badge-neutral {
     @layer daisyui.l1.l2 {
       --badge-color: var(--color-neutral);