feat: implement scoped stat system with player/global support

Introduces a scoping mechanism for statistics, allowing properties
to be defined as either "player" (prefixed with player name) or
"global".

- Adds `scope` property to StatDef
- Implements key resolution to handle bare keys vs full keys
- Updates `canModifyStat` to enforce player-specific permissions
- Enhances `makeStatLookup` to resolve scoped references in formulas
- Adds documentation for the new stat system

src/components/journal/JournalInput.tsx

@@ -15,7 +15,7 @@ import { actionPrefill, setActionPrefill } from "../stores/reveal";
 import { useJournalCompletions, ensureCompletions } from "./completions";
 import { resolveRollPayload } from "./types/roll";
 import { resolveSparkPayload } from "./types/spark";
-import { resolveStatRoll, canModifyStat } from "./stat-helpers";
+import { resolveStatRoll, canModifyStat, fullKey } from "./stat-helpers";
 import { parseInput } from "./command-parser";
 import type { CompletionItem } from "./command-parser";
 import { buildCompletions } from "./command-completions";
@@ -147,13 +147,18 @@ export const JournalInput: Component = () => {
     const p = payload as { action?: string; key?: string; value?: string };
 
     if (p.action === "roll" && p.key) {
-      const resolved = resolveStatRoll(p.key, comp.data.stats, stream.stats);
+      const resolved = resolveStatRoll(
+        p.key,
+        comp.data.stats,
+        stream.stats,
+        stream.myName,
+      );
       if (resolved.error) {
         setError(resolved.error);
       } else {
         const result = sendMessage("stat", {
           action: "set",
-          key: p.key,
+          key: resolved.fullKey,
           value: resolved.value,
         });
         const r = unwrap(result);
@@ -167,16 +172,38 @@ export const JournalInput: Component = () => {
       return;
     }
 
-    if (!canModifyStat(stream.myRole, stream.myName, p.key)) {
+    // Resolve bare key to full key for set/del
+    const fk = resolveKey(p.key, comp.data.stats, stream.myName);
+
+    if (!canModifyStat(stream.myRole, stream.myName, fk, comp.data.stats)) {
       setError(`无权修改属性: ${p.key}`);
       return;
     }
 
-    const result = sendMessage("stat", payload);
+    const result = sendMessage("stat", {
+      action: p.action,
+      key: fk,
+      value: p.value,
+    });
     const r = unwrap(result);
     finish(r.ok, r.err);
   }
 
+  /** Resolve a bare or full key to the actual runtime key. */
+  function resolveKey(
+    inputKey: string,
+    statDefs: typeof comp.data.stats,
+    playerName: string,
+  ): string {
+    // Exact match
+    if (statDefs.some((d) => fullKey(d, playerName) === inputKey))
+      return inputKey;
+    // Bare key → full key
+    const def = statDefs.find((d) => d.key === inputKey);
+    if (def) return fullKey(def, playerName);
+    return inputKey;
+  }
+
   /** Clear text + error on success, or set error on failure. */
   function finish(success: boolean, err?: string) {
     if (success) {