WIP: restore lost C behaviors (schtick message, forced redraw, greeting)

Incomplete checkpoint, preserved after the implementing session hit a
capacity limit partway through mutation verification. NOT reviewed and NOT
gate-clean: make fmt has not been run, so fmt-check currently fails on
ARCHITECTURE.md and TODO.md.

Work still outstanding before this is fit for review:
  - run make fmt and fold the result in
  - finish mutation-proving each of the three behaviors
  - verify every message string byte-for-byte against the C sources
  - confirm TestSeedCompatItemTables passes with its golden untouched

Refs #13.

game/game.go

@@ -1,6 +1,8 @@
 //nolint:mnd // C-faithful literals; names hurt C-greppability (approved 2026-07-07)
 package game
 
+import "fmt"
+
 // ItemLore is the per-game item identity state: the randomized appearance
 // names and the seven mutable ObjInfo tables (extern.c/init.c).
 type ItemLore struct {
@@ -151,6 +153,43 @@ type RogueGame struct {
 	data *gameData
 }
 
+// Greeting is the line C printed on stdout while the player waited for
+// the dungeon to be dug, immediately before initscr() (main.c main). The
+// caller prints it before the terminal package takes the screen, which is
+// where initscr() sat; there is no trailing newline in either wording,
+// because C followed the printf with fflush and let curses have the
+// display.
+//
+// Only the wizard wording is #ifdef MASTER in C, and it carries the
+// dungeon number, which is the seed (main.c assigns seed = dnum right
+// after choosing dnum). The other wording is unconditional.
+//
+// The name is C's whoami, resolved the way main.c resolves it: parse_opts
+// runs before the printf, so a ROGUEOPTS "name=" setting is what the
+// player is greeted by, and the account name is only the fallback. New
+// does the same parse a moment later; doing it here too is safe because
+// ParseOpts does nothing but assign into the fields it is handed — no
+// RNG, no screen — so it cannot disturb the item tables the seed-compat
+// golden pins.
+func Greeting(params Params) string {
+	whoami := params.Name
+
+	if params.RogueOpts != "" {
+		opts := &RogueGame{Whoami: params.Name}
+		opts.ParseOpts(params.RogueOpts)
+
+		whoami = opts.Whoami
+	}
+
+	if params.Wizard {
+		return fmt.Sprintf("Hello %s, welcome to dungeon #%d",
+			whoami, params.Seed)
+	}
+
+	return fmt.Sprintf(
+		"Hello %s, just a moment while I dig the dungeon...", whoami)
+}
+
 // New builds a game from params, seeds the RNG, and randomizes the item
 // appearance tables (the front half of main.c main(); the player roll-up
 // and first level arrive with later porting phases).