feat(discordsh): integrate bevy_quests proto-driven quest system

[h0lybyte]

Summary

• Integrate bevy_quests crate into DiscordSH dungeon crawler with full quest lifecycle (accept, progress, complete, abandon)
• Create 6 dungeon quests: 3-quest main chain (Dungeon Delver → Shadow Hunter → King's Demise) + 3 standalone (Slime Slayer, Treasure Seeker, Survivor)
• Add QuestJournal state tracking on SessionState with automatic objective progression on enemy kills and room exploration
• 662 tests pass including 44 new quest-specific tests

Changes

• Added bevy_quests dependency to axum-discordsh
• Created data/questdb.json with 6 quests in proto-compatible format
• Created 6 MDX content docs for quest documentation
• Added QuestJournal, ActiveQuest, ObjectiveProgress, StepProgress types to types.rs
• Added QuestDb LazyLock loading + helper functions to proto_bridge.rs
• Wired quest progression into combat (kill objectives) and exploration (room visits) in logic.rs
• Added AcceptQuest, AbandonQuest, ViewQuests game actions
• Updated Dockerfile and Dockerfile.base for bevy_quests build stages

Test plan

• 28 proto_bridge quest tests (DB loading, prerequisites, quest chains, rewards)
• 16 logic integration tests (accept/abandon/view, kill/explore advancement, completions, repeatable, multi-step)
• Full suite: 662 tests pass

Closes #8111 (Phase 3b)

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None