refactor: extract Evidence DSL to @arbiter/evidence-dsl package

The Evidence DSL (ADR-000) compiles a natural DSL into core rule
configurations — it is a separate concern from the engine. The AST had
zero runtime coupling to the core (DSLCompiler takes the arbiter as a
duck-typed argument; ip-utils were the only shared code, now local to
the DSL package). This extraction removes the DSL surface from the core
artifact entirely:

- src/ast/ (748K, ~60 files) moved to @arbiter/evidence-dsl@1.0.0
- ip-utils moved with it (only the DSL consumed them)
- generate-parser script + peggy devDep moved to the DSL package
- the 8 DSL-consuming tests now import from @arbiter/evidence-dsl
  (deep-path exports: DSLCompiler, parser/*, generator/*, validation/*,
  interpreter/*)
- package.json gains the devDependency, drops build:ast/generate:parser

Tarball: AST-free. Rigor 251/251, full suite 838/776/0.

scripts/generate-parser.js

@@ -1,51 +0,0 @@
-#!/usr/bin/env node
-
-/**
- * Script to generate the DSL parser from Peggy grammar
- */
-
-import peggy from 'peggy';
-import fs from 'fs';
-import path from 'path';
-import { fileURLToPath } from 'url';
-
-const __filename = fileURLToPath(import.meta.url);
-const __dirname = path.dirname(__filename);
-
-const grammarPath = path.join(__dirname, '../src/ast/grammar/dsl.peggy');
-const outputPath = path.join(__dirname, '../src/ast/parser/GeneratedParser.js');
-
-console.log('Generating DSL parser from Peggy grammar...');
-console.log('Grammar:', grammarPath);
-console.log('Output:', outputPath);
-
-try {
-  // Read the grammar file
-  const grammar = fs.readFileSync(grammarPath, 'utf8');
-  
-  // Generate the parser
-  const parserSource = peggy.generate(grammar, {
-    format: 'es',
-    output: 'source',
-    grammarSource: 'dsl.peggy'
-  });
-  
-  // Write the generated parser
-  fs.writeFileSync(outputPath, parserSource);
-  
-  console.log('✅ Parser generated successfully!');
-  console.log('Generated file:', outputPath);
-  
-} catch (error) {
-  console.error('❌ Error generating parser:');
-  console.error(error.message);
-  
-  if (error.format) {
-    console.error('\nFormatted error:');
-    console.error(error.format([
-      { source: 'dsl.peggy', text: fs.readFileSync(grammarPath, 'utf8') }
-    ]));
-  }
-  
-  process.exit(1);
-}