feat(tournament): implement hunting tournament system end-to-end

Wire format for MsgMhfEnterTournamentQuest (0x00D2) derived from
mhfo-hd.dll binary analysis (FUN_114f4280). Five new tables back
the full lifecycle: schedule, cups, sub-events, player registrations,
and run submissions. All six tournament handlers are now DB-driven:

- EnumerateRanking: returns active tournament schedule with cups and
  sub-events; computes phase state byte from timestamps
- EnumerateOrder: returns per-event leaderboard ranked by submission
  time, with SJIS-encoded character and guild names
- InfoTournament: exposes tournament detail and player registration
  state across all three query types
- EntryTournament: registers player and returns entry handle used by
  the client in the subsequent EnterTournamentQuest packet
- EnterTournamentQuest: parses the previously-unimplemented packet and
  records the run in tournament_results
- AcquireTournament: stubs rewards (item IDs not yet reversed)

Seed data (TournamentDefaults.sql) reproduces tournament #150 cups and
sub-events so a fresh install has a working tournament immediately.

server/migrations/sql/0015_tournament.sql

@@ -0,0 +1,48 @@
+BEGIN;
+
+CREATE TABLE IF NOT EXISTS tournaments (
+    id          SERIAL PRIMARY KEY,
+    name        VARCHAR(64) NOT NULL,
+    start_time  BIGINT NOT NULL,
+    entry_end   BIGINT NOT NULL,
+    ranking_end BIGINT NOT NULL,
+    reward_end  BIGINT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS tournament_cups (
+    id            SERIAL PRIMARY KEY,
+    tournament_id INTEGER NOT NULL REFERENCES tournaments(id) ON DELETE CASCADE,
+    cup_group     SMALLINT NOT NULL,
+    cup_type      SMALLINT NOT NULL,
+    unk           SMALLINT NOT NULL DEFAULT 0,
+    name          VARCHAR(64) NOT NULL,
+    description   TEXT NOT NULL DEFAULT ''
+);
+
+CREATE TABLE IF NOT EXISTS tournament_sub_events (
+    id             SERIAL PRIMARY KEY,
+    cup_group      SMALLINT NOT NULL,
+    event_sub_type SMALLINT NOT NULL DEFAULT 0,
+    quest_file_id  INTEGER NOT NULL DEFAULT 0,
+    name           VARCHAR(64) NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS tournament_entries (
+    id            SERIAL PRIMARY KEY,
+    char_id       INTEGER NOT NULL REFERENCES characters(id) ON DELETE CASCADE,
+    tournament_id INTEGER NOT NULL REFERENCES tournaments(id) ON DELETE CASCADE,
+    registered_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (char_id, tournament_id)
+);
+
+CREATE TABLE IF NOT EXISTS tournament_results (
+    id            SERIAL PRIMARY KEY,
+    char_id       INTEGER NOT NULL REFERENCES characters(id) ON DELETE CASCADE,
+    tournament_id INTEGER NOT NULL REFERENCES tournaments(id) ON DELETE CASCADE,
+    event_id      INTEGER NOT NULL,
+    quest_slot    INTEGER NOT NULL DEFAULT 0,
+    stage_handle  INTEGER NOT NULL DEFAULT 0,
+    submitted_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+COMMIT;