docs: adopt unified-3.0 Claude rule set + trim duplications

Adopts the four-file rule set the player added to the working tree:

- CLAUDE.md grows from a 114-line pointer doc to the 571-line
  `unified-3.0` rulebook: hard global constraints (§2), engine
  rules (§3), asset rules (§4), code standards (§5), build +
  verification (§6), git workflow (§7), the change-control
  ASK BEFORE list (§8), and the Context Injection System (§14).
- CLAUDE_SPEC.md — formal architecture spec: crate dependency
  graph with forbidden_deps, data ownership map, state-machine
  invariants ("52 cards always exist", "no duplicate IDs",
  "all cards belong to exactly one pile"), sync merge contract,
  server contract, validation checklist.
- CLAUDE_WORKFLOW.md — two-agent Builder/Guardian pipeline with
  hard-fail patterns that auto-reject (core uses IO/Bevy/network,
  GameState mutated outside GameLogicSystem, blocking async on
  main thread, duplicate logic, merge altered incorrectly).
- CLAUDE_PROMPT_PACK.md — task-type templates.

Three duplicate rule passages removed:

- CLAUDE_SPEC.md §0 dropped no_panics_in_core / core_is_pure /
  event_driven_engine — already canonical in CLAUDE.md §2.1, §2.3,
  §3.1. Kept single_source_of_truth and sync_is_additive (those
  describe data flow, not in CLAUDE.md).
- CLAUDE_SPEC.md §11 Prohibited Patterns now references CLAUDE.md
  §11 instead of restating the same five forbidden items.
- ARCHITECTURE.md Design Principles dropped the pure-core /
  no-panics / UI-first bullets — those are enforcement constraints
  living in CLAUDE.md §2.1, §2.3, §3.3; this file describes the
  design that motivates them. Kept the offline-first, one-language,
  and plugin-based-Bevy bullets (those are descriptive, not
  enforcement).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ARCHITECTURE.md

@@ -47,11 +47,10 @@ Solitaire Quest is a cross-platform Klondike Solitaire game written in Rust, tar
 ### Design Principles
 
 - **Offline first.** The local file is always the source of truth. Sync is additive, never destructive.
-- **Pure core.** All game logic lives in a dependency-free Rust crate with no Bevy, no network, and no I/O. This keeps it fully unit-testable and portable.
-- **No panics in game logic.** Every state transition returns `Result<_, MoveError>`. Panics are only acceptable in startup/configuration code.
 - **One language, one repo.** The game client, sync client, shared types, and sync server are all Rust crates in a single Cargo workspace.
 - **Plugin-based Bevy architecture.** Each major feature is a Bevy `Plugin`. Systems are small and single-purpose. Cross-system communication uses Bevy `Event`s.
-- **UI-first interaction.** Every player-triggered action — new game, undo, draw, pause, open stats / settings / help / profile / leaderboard, etc. — must be reachable from a visible UI control. Keyboard shortcuts exist only as optional accelerators for power users; they are never the sole entry point. A player using only mouse or touch must be able to perform every action. New gameplay features ship with the UI control alongside the system that backs it.
+
+Pure-core, no-panics-in-game-logic, and UI-first-interaction constraints are enforced by CLAUDE.md §2.1, §2.3, and §3.3 respectively — those are the canonical statements; this file describes the design that motivates them.
 
 ---