FT fix CI #340: re-seed Earthman deck in GameboardNavigationTest setUp — TransactionTestCase flush trap

`test_game_kit_panel_shows_token_inventory` (a133a9c's polish-9 FT fix) was looking for `id_kit_earthman_deck` in the Game Kit applet. CI #340 surfaced that the selector wasn't rendering — same `TransactionTestCase` migration-seed flush trap documented in `feedback_transactiontestcase_flush.md`:

1. `LiveServerTestCase` derives from `TransactionTestCase` → DB flushed between tests → migration-seeded `DeckVariant(slug="earthman")` row vanishes.
2. `apps/lyric/models.py:537`'s `DeckVariant.objects.filter(slug="earthman").first()` returns None in the post_save signal → `unlocked_decks.add(earthman)` silently skipped.
3. Gameboard view passes `request.user.unlocked_decks.all()` as `deck_variants` → empty → applet partial falls through to `{% empty %}` `id_kit_card_deck` placeholder instead of the per-deck `id_kit_{{ deck.short_key }}_deck` element the FT expects.

Fix mirrors the 14+ other FTs already using this helper: call `_seed_earthman_sig_pile()` in `setUp` before `create_pre_authenticated_session` fires the signal. The helper is `get_or_create`-based + idempotent.

Selector itself was NOT renamed — `short_key = slug.split('-')[0]` still yields `"earthman"` from slug `"earthman"`, so `id_kit_earthman_deck` is correct.

Verified locally: the test runs green w. the seed call in place.

Pre-existing in `git status`, bundled per project commit-everything rule:
- `src/.coveragerc` — add `*/delete_stale_my_sea_draws.py` to coverage omit list (one-off management script doesn't need coverage measurement)

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Sonnet 4.6 <noreply@anthropic.com>

src/.coveragerc

@@ -5,6 +5,7 @@ omit =
     */tests/*
     */routing.py
     */reset_staging_db.py
+    */delete_stale_my_sea_draws.py
 
 [report]
 show_missing = true

src/functional_tests/test_gameboard.py

@@ -3,6 +3,7 @@ from selenium.webdriver.common.action_chains import ActionChains
 from selenium.webdriver.common.by import By
 
 from .base import FunctionalTest
+from .sig_page import _seed_earthman_sig_pile
 from apps.applets.models import Applet
 from apps.epic.models import DeckVariant, Room
 from apps.lyric.models import Token, User
@@ -11,6 +12,17 @@ from apps.lyric.models import Token, User
 class GameboardNavigationTest(FunctionalTest):
     def setUp(self):
         super().setUp()
+        # Re-seed the Earthman DeckVariant up front — TransactionTestCase
+        # flushes migration data between tests, so by the time the user
+        # is created (`create_pre_authenticated_session` inside each test
+        # method), the post_save signal in `apps/lyric/models.py:537`'s
+        # `DeckVariant.objects.filter(slug="earthman").first()` would
+        # return None + skip `unlocked_decks.add(earthman)`. That left
+        # `test_game_kit_panel_shows_token_inventory`'s `id_kit_earthman_
+        # deck` selector unrenderable (applet falls through to the
+        # `{% empty %}` `id_kit_card_deck` placeholder). CI #340 trap.
+        # See [[feedback-transactiontestcase-flush]].
+        _seed_earthman_sig_pile()
         Applet.objects.get_or_create(slug="new-game", defaults={"name": "New Game", "context": "gameboard"})
         Applet.objects.get_or_create(slug="my-games", defaults={"name": "My Games", "context": "gameboard"})
         Applet.objects.get_or_create(slug="game-kit", defaults={"name": "Game Kit", "context": "gameboard"})