Remove the TUI; the web app is the frontend

money serve covers every screen the TUI had, so keeping both meant every
behaviour change landing twice. internal/tui goes, and with it bubbletea,
bubbles and lipgloss. `money` with no command now runs serve, the way it
used to open the TUI, and `money tui` is an unknown command.

Three invariants in CLAUDE.md were covered only by TUI tests. Two already
had web counterparts; TestPairedLegsAreNotUntagged is ported to the API:
a paired leg is neither listed as untagged nor offered to the rule
builder, while an unpaired one still is.

README's screen sections now describe the browser, which kept the
behaviour and changed only the controls. CLAUDE.md names the web
equivalents of the TUI functions its invariants pointed at, drops the tab
completion rule that only bubbles' textinput needed, and says how to test
the web app instead of how to drive a terminal.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/store/store.go

@@ -393,7 +393,7 @@ func (d *DB) Months() ([]string, error) {
 	return out, rows.Err()
 }
 
-// Tags lists every tag in use, for completion in the TUI.
+// Tags lists every tag in use, for completion in the rule builder.
 func (d *DB) Tags() ([]string, error) {
 	rows, err := d.sql.Query(`
 		SELECT DISTINCT rule_tag FROM transactions