refactor: optimize reactive variable updates and parsing

- Replace `scanDeclareBlocks` with `parseDeclareCsv` in block processor
- Add error handling for declare block parsing
- Optimize `ReactiveVariableManager` by pre-computing variable keys
- Store template text and keys in data attributes for faster updates
- Adjust `VariableView` popup width via CSS class

src/cli/completions/block-processor.ts

@@ -7,7 +7,7 @@
 
 import { posix } from "path";
 import { createHash } from "crypto";
-import { scanDeclareBlocks, type VarDeclaration, type TagModifier } from "./declare-parser.js";
+import { parseDeclareCsv, type VarDeclaration, type TagModifier } from "./declare-parser.js";
 import {
   FENCED_BLOCK_RE,
   parseBlockAttrs,
@@ -86,9 +86,13 @@ export function processBlocks(
       // ---- Dispatch by role ----
 
       if (attrs.role === "declare") {
-        const result = scanDeclareBlocks(_match, fileRelativePath);
-        blocks.declarations.push(...result.variables);
-        blocks.tagModifiers.push(...result.tagModifiers);
+        try {
+          const result = parseDeclareCsv(body, fileRelativePath);
+          blocks.declarations.push(...result.variables);
+          blocks.tagModifiers.push(...result.tagModifiers);
+        } catch (e) {
+          console.warn(`[block-processor] ${fileRelativePath}: ${e}`);
+        }
       }
 
       if (attrs.role === "file") {