refactor(bin): replace process.exit() in CLI entrypoints + ratchet rule to error (#738) (#741)

Part 2 of 2 of the n/no-process-exit cleanup (completes umbrella #738; part 1
was #739/scripts). Converts the 20 flagged process.exit() calls in the three
hand-written gsd-core/bin CLI entrypoints and flips n/no-process-exit to error.

- New src/cli-exit.cts -> gsd-core/bin/lib/cli-exit.cjs (ExitError + runMain),
  the gsd-core-side equivalent of scripts/lib/cli-exit.cjs; registered in
  .gitignore, eslint ignores, and the inventory manifest like its siblings.
- gsd-tools.cjs: 13 apply-prompt-budget exits -> throw ExitError; main()->runMain.
- verify-reapply-patches.cjs: 6 exits -> throw ExitError / return verdict; runMain.
- check-latest-version.cjs: 1 exit -> return verdict; runMain.
- eslint.config.mjs: n/no-process-exit warn -> error.

Scope note: the gsd-core/bin/lib/*.cjs modules (core, state, profile-pipeline,
roadmap-command-router, adr-parser, ui-safety-gate) are tsc-generated and
eslint-ignored (ADR-457), so their process.exit calls were never flagged and are
intentionally left untouched. Only the linted hand-written entrypoints are in scope.

Exit codes verified unchanged for all three entrypoints.

Closes #738

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

docs/INVENTORY-MANIFEST.json

@@ -1,5 +1,5 @@
 {
-  "generated": "2026-06-05",
+  "generated": "2026-06-06",
   "families": {
     "agents": [
       "gsd-advisor-researcher",
@@ -272,6 +272,7 @@
       "audit.cjs",
       "check-command-router.cjs",
       "cjs-command-router-adapter.cjs",
+      "cli-exit.cjs",
       "clock.cjs",
       "clusters.cjs",
       "code-review-flags.cjs",

docs/INVENTORY.md

@@ -370,7 +370,7 @@ The `gsd-planner` agent is decomposed into a core agent plus reference modules t
 
 ---
 
-## CLI Modules (85 shipped)
+## CLI Modules (86 shipped)
 
 Full listing: `gsd-core/bin/lib/*.cjs`.
 
@@ -382,6 +382,7 @@ Full listing: `gsd-core/bin/lib/*.cjs`.
 | `artifacts.cjs` | Canonical artifact registry — known `.planning/` root file names; used by `gsd-health` W019 lint |
 | `audit.cjs` | Audit dispatch, audit open sessions, audit storage helpers |
 | `check-command-router.cjs` | Thin CJS subcommand router adapter for `gsd-tools check` |
+| `cli-exit.cjs` | `ExitError` class and `runMain()` helper — CLI entrypoints throw `ExitError` instead of calling `process.exit()`; `runMain()` translates the outcome into `process.exitCode` so output flushes cleanly |
 | `cjs-command-router-adapter.cjs` | Shared compatibility adapter for manifest-backed CJS command-family routers |
 | `clock.cjs` | Injectable clock seam (now/sleep) for deterministic lock testing |
 | `clusters.cjs` | Skill cluster definitions for the runtime surface module (ADR-0011 Phase 2) |