refactor: resolve conflicts — merge packages/shared into packages/cli/src/shared (#2092)

Rebased fix/issue-2083 onto main after commands.ts split (PR #2095).
Key resolutions:
- commands.ts: kept HEAD shim (re-exports from ./commands/index.ts)
- package.json: kept PR version 0.12.0 without @openrouter/spawn-shared dep
- Fixed @openrouter/spawn-shared imports in commands/shared.ts, commands/update.ts,
  and __tests__/orchestrate.test.ts that were added after the PR branched

All 1390 tests pass, biome lint clean.

Agent: pr-maintainer

Co-authored-by: B <6723574+louisgv@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

bun.lock

@@ -14,13 +14,12 @@
     },
     "packages/cli": {
       "name": "@openrouter/spawn",
-      "version": "0.10.3",
+      "version": "0.11.24",
       "bin": {
         "spawn": "cli.js",
       },
       "dependencies": {
         "@clack/prompts": "1.0.0",
-        "@openrouter/spawn-shared": "workspace:*",
         "picocolors": "1.1.1",
         "valibot": "1.2.0",
       },
@@ -31,7 +30,7 @@
     },
     "packages/shared": {
       "name": "@openrouter/spawn-shared",
-      "version": "0.1.0",
+      "version": "0.1.1",
       "dependencies": {
         "valibot": "1.2.0",
       },