feat(omo-codex): add post-compact rule budget to codex hook

Trim rule and result char budgets after compaction via new
postCompactMaxRuleChars/postCompactMaxResultChars config, applied
through withPostCompactBudget. Extract codex-hook helpers into
dynamic-target-fingerprints, hook-output, path-utils,
rules-engine-factory, and transcript-rule-filter modules.

packages/omo-codex/plugin/components/rules/src/rules-engine-factory.ts

@@ -0,0 +1,24 @@
+import { readFileSync } from "node:fs";
+
+import { configFromEnvironment } from "./config.js";
+import { createEngine } from "./rules/engine.js";
+import { findRuleCandidates } from "./rules/finder.js";
+import { findProjectRoot } from "./rules/project-root.js";
+
+interface RulesEngineFactoryOptions {
+	env?: NodeJS.ProcessEnv;
+}
+
+export function createRulesEngine(options: RulesEngineFactoryOptions, config = configFromEnvironment(options.env)) {
+	return createEngine(config, {
+		findCandidates: findRuleCandidates,
+		findProjectRoot,
+		readFile: (path) => {
+			try {
+				return readFileSync(path, "utf8");
+			} catch {
+				return null;
+			}
+		},
+	});
+}