chore(claude): add private-name rule

Mirror of the rule landed in socket-lib + socket-repo-template. Omit
private repo and internal project names from public-surface text;
don't substitute a placeholder.

Author: jdalton

CLAUDE.md

@@ -42,6 +42,7 @@ The umbrella rule: never run a git command that mutates state belonging to a pat
 - Backward Compatibility: 🚨 FORBIDDEN to maintain — actively remove when encountered
 - 🚨 **NEVER use `npx`, `pnpm dlx`, or `yarn dlx`** — use `pnpm exec <package>` or `pnpm run <script>`. Add tools as pinned devDependencies first.
 - **minimumReleaseAge**: NEVER add packages to `minimumReleaseAgeExclude` in CI. Locally, ASK before adding — the age threshold is a security control.
+- 🚨 **NEVER mention private repos or internal project names** in commits, PR titles/descriptions/comments, issues, release notes, or any public-surface text. Internal codenames, unreleased product names, internal tooling repo names not on the public org page, customer names, partner names — none belong in public surfaces. **Omit the reference entirely.** Don't substitute a placeholder ("an internal tool", "a downstream consumer", etc.) — the placeholder itself is a tell that something is being elided. Rewrite the sentence to not need the reference at all.
 - File existence: ALWAYS `existsSync` from `node:fs`. NEVER `fs.access`, `fs.stat`-for-existence, or an async `fileExists` wrapper. Import form: `import { existsSync, promises as fs } from 'node:fs'`.
 - Null-prototype objects: ALWAYS use `{ __proto__: null, ...rest }` for config, return, and internal-state objects. Prevents prototype pollution and accidental inheritance. See `src/socket-sdk-class.ts` and `src/file-upload.ts` for examples.
 - Linear references: NEVER reference Linear issues (e.g. `SOC-123`, `ENG-456`, Linear URLs) in code, code comments, or PR titles/descriptions/review comments. Keep the codebase and PR history tool-agnostic — tracking lives in Linear.