feat(03-04): replace Paperclip display strings in CLI entry point and HTTP client

- Add VOCAB import to cli/src/index.ts and cli/src/client/http.ts
- Replace all 'Paperclip' description/help strings with VOCAB.appName
- Update backup filename prefix default from 'paperclip' to 'nexus'
- Update data dir help text to reference ~/.nexus
- Keep .name('paperclipai') binary name unchanged (CODE-zone)

cli/src/client/http.ts

@@ -1,4 +1,5 @@
 import { URL } from "node:url";
+import { VOCAB } from "@paperclipai/branding"; // [nexus]
 
 export class ApiRequestError extends Error {
   status: number;
@@ -205,7 +206,7 @@ function buildConnectionErrorMessage(input: {
 }): string {
   const healthUrl = buildHealthCheckUrl(input.url);
   const lines = [
-    "Could not reach the Paperclip API.",
+    `Could not reach the ${VOCAB.appName} API.`, // [nexus]
     "",
     `Request: ${input.method} ${input.url}`,
   ];
@@ -214,12 +215,12 @@ function buildConnectionErrorMessage(input: {
   }
   lines.push(
     "",
-    "This usually means the Paperclip server is not running, the configured URL is wrong, or the request is being blocked before it reaches Paperclip.",
+    `This usually means the ${VOCAB.appName} server is not running, the configured URL is wrong, or the request is being blocked before it reaches ${VOCAB.appName}.`, // [nexus]
     "",
     "Try:",
-    "- Start Paperclip with `pnpm dev` or `pnpm paperclipai run`.",
+    `- Start ${VOCAB.appName} with \`pnpm dev\` or \`pnpm paperclipai run\`.`, // [nexus]
     `- Verify the server is reachable with \`curl ${healthUrl}\`.`,
-    `- If Paperclip is running elsewhere, pass \`--api-base ${input.apiBase.replace(/\/+$/, "")}\` or set \`PAPERCLIP_API_URL\`.`,
+    `- If ${VOCAB.appName} is running elsewhere, pass \`--api-base ${input.apiBase.replace(/\/+$/, "")}\` or set \`PAPERCLIP_API_URL\`.`, // [nexus]
   );
   return lines.join("\n");
 }

cli/src/index.ts

@@ -20,14 +20,15 @@ import { loadPaperclipEnvFile } from "./config/env.js";
 import { registerWorktreeCommands } from "./commands/worktree.js";
 import { registerPluginCommands } from "./commands/client/plugin.js";
 import { registerClientAuthCommands } from "./commands/client/auth.js";
+import { VOCAB } from "@paperclipai/branding"; // [nexus]
 
 const program = new Command();
 const DATA_DIR_OPTION_HELP =
-  "Paperclip data directory root (isolates state from ~/.paperclip)";
+  `${VOCAB.appName} data directory root (isolates state from ~/.nexus)`; // [nexus]
 
 program
   .name("paperclipai")
-  .description("Paperclip CLI — setup, diagnose, and configure your instance")
+  .description(`${VOCAB.appName} CLI — setup, diagnose, and configure your instance`) // [nexus]
   .version("0.2.7");
 
 program.hook("preAction", (_thisCommand, actionCommand) => {
@@ -46,12 +47,12 @@ program
   .option("-c, --config <path>", "Path to config file")
   .option("-d, --data-dir <path>", DATA_DIR_OPTION_HELP)
   .option("-y, --yes", "Accept defaults (quickstart + start immediately)", false)
-  .option("--run", "Start Paperclip immediately after saving config", false)
+  .option("--run", `Start ${VOCAB.appName} immediately after saving config`, false) // [nexus]
   .action(onboard);
 
 program
   .command("doctor")
-  .description("Run diagnostic checks on your Paperclip setup")
+  .description(`Run diagnostic checks on your ${VOCAB.appName} setup`) // [nexus]
   .option("-c, --config <path>", "Path to config file")
   .option("-d, --data-dir <path>", DATA_DIR_OPTION_HELP)
   .option("--repair", "Attempt to repair issues automatically")
@@ -83,7 +84,7 @@ program
   .option("-d, --data-dir <path>", DATA_DIR_OPTION_HELP)
   .option("--dir <path>", "Backup output directory (overrides config)")
   .option("--retention-days <days>", "Retention window used for pruning", (value) => Number(value))
-  .option("--filename-prefix <prefix>", "Backup filename prefix", "paperclip")
+  .option("--filename-prefix <prefix>", "Backup filename prefix", "nexus") // [nexus]
   .option("--json", "Print backup metadata as JSON")
   .action(async (opts) => {
     await dbBackupCommand(opts);
@@ -99,7 +100,7 @@ program
 
 program
   .command("run")
-  .description("Bootstrap local setup (onboard + doctor) and run Paperclip")
+  .description(`Bootstrap local setup (onboard + doctor) and run ${VOCAB.appName}`) // [nexus]
   .option("-c, --config <path>", "Path to config file")
   .option("-d, --data-dir <path>", DATA_DIR_OPTION_HELP)
   .option("-i, --instance <id>", "Local instance id (default: default)")
@@ -117,7 +118,7 @@ heartbeat
   .option("-d, --data-dir <path>", DATA_DIR_OPTION_HELP)
   .option("--context <path>", "Path to CLI context file")
   .option("--profile <name>", "CLI context profile name")
-  .option("--api-base <url>", "Base URL for the Paperclip server API")
+  .option("--api-base <url>", `Base URL for the ${VOCAB.appName} server API`) // [nexus]
   .option("--api-key <token>", "Bearer token for agent-authenticated calls")
   .option(
     "--source <source>",