refactor(cli): Phase 4 cleanup — dedup, extract, deprecate

- bundle-store.ts: remove private pathExists, import from fs-utils
- thread-scan.ts: extract parseFirstJsonLineObject helper, dedup first-line parsing
- commands/workflow/add-argv.ts: extract parseAddArgv from add.ts
- commands/thread/fork-argv.ts: extract parseForkArgv from fork.ts
- commands/cas/*.ts: remove unused _threadId params from cmdCas* functions
- cli-dispatch.ts: add deprecation warning to help command
- commands/init/templates.ts: extract template strings from template.ts
- cli-color.ts: extract shouldUseColor, highlightLiveRole, dimGreyLine from live.ts
- 242 tests pass, biome clean

Closes #97

packages/cli-workflow/__tests__/thread-cli.test.ts

@@ -232,7 +232,7 @@ describe("cli thread commands", () => {
     const runningPath = join(dirname(dataPath), `${threadId}.running`);
     await waitUntilRunningFileAbsent(runningPath, 120);
 
-    const put = await cmdCasPut(storageRoot, threadId, "keep-after-thread-rm");
+    const put = await cmdCasPut(storageRoot, "keep-after-thread-rm");
     expect(put.ok).toBe(true);
     if (!put.ok) {
       return;