Guardian boss bars; Phase 7 approved

Adrian, 2026-11-03: guardians get a boss health bar like the Wither's, which
also leads players to them. Every player within 128 blocks of a living
guardian sees a red bar of their own (GuardianBars): name, zone, how many
blocks away, and HP. The End boss keeps the dragon's bar.
guardian_appears_and_returns checks the bar appears and goes once beaten.
Self-tests and the island check pass.

Phase 7 approved ("Then begin with the next phase"); README status updated.

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

docs/design.md

@@ -294,6 +294,8 @@ Self-tests (`BossTests`): every guardian has a fight and a Cobblemon model; each
 
 **Bosses are big and tough, not strong** (Adrian, 2026-11-02: Eternatus was too small and too easy; guardians should be way bigger and tougher; only defensive stats go up, never Attack or Speed; no single attack may take more than a quarter of a boss's HP). Every boss (guardian, End boss, practice copy) is scaled to stand about 8 blocks tall (Eternatus 15; `tools/zone_spawns.py`, `tools/zone_bosses.py`) and gets perfect IVs and 170 EVs each in HP, Defense and Sp. Def, nothing offensive (`BossToughness`). In battle it brings the **Guardian's Ward**, a held item that exists only inside Cobblemon's battle engine (Showdown): Cobblemon loads it from `datapacks/core/data/cobblesurvival/held_items/guardiansward.js`, and the companion mod hands it to every boss ahead of whatever it holds, so it can't be stolen, knocked off or suppressed. It starts a lasting condition that doubles Defense and Sp. Def while the boss defends (not for Body Press) and caps one attack, all hits of a multi-hit move together, at a quarter of the boss's max HP. Guardians and an Eternatus already standing in a world grow and get their training on the next check outside battle; a cave guardian moves to a spot it fits in. Area attacks that start at the boss (rings, lines, cones) reach half its width further, so a big boss's ring starts at its edge. Self-tests: `practice_bosses_spawn` (size, training, full health) and `boss_takes_a_quarter_per_attack` (a real battle: a Lv 100 Garchomp's Bullet Seed, every hit enough to knock out the Lv 15 boss, takes exactly a quarter per use).
 
+**Guardian boss bars** (Adrian, 2026-11-03: a boss health bar like the Wither's, which also leads players to the guardian). Every player within 128 blocks of a living guardian sees a red bar of their own (`GuardianBars`): the guardian's name, its zone and how many blocks away it is, and its HP, which falls in battle. Walking around, the number tells players whether they're getting closer; no other hint (Adrian, 2026-11-02). The End boss keeps the dragon's bar.
+
 **The End has Pokémon** (Adrian, 2026-11-02: it looked barren). The End is a zone of its own, "The End", Lv 50–70 (`world/zones.json` → `dimensions`; `Zones.at` returns it anywhere in the End). Every line Cobblemon spawns in End biomes spawns there too, on top of its home on the island: Beheeyem, Reuniclus and Metagross anywhere; Gothitelle and Sigilyph in End cities; Malamar and Unown with a Poké Snack. Gothita had no island home (it only spawns in the End), so it's new. Cobblemon has all of these uncommon or rare, and it rolls the bucket before the Pokémon, so in the End they move to the common bucket or the End would stay nearly empty; each line weighs the same, Metagross a fifth. Being a zone, the End also has level pressure (full experience up to Lv 75, like the Basalt Furnace) and the wild-Pokémon cleanup above Lv 80; Eternatus is exempt as an uncatchable boss. Self-test `end_has_spawns`.
 
 ## Open decisions for Adrian (proceeding with the default, flagged)