Initial commit: move CLI (milestone 2)

- src/move.ts entry point with CLI parsing, --help, --version
- src/cli.ts: parseCliArgs, printHelp, ParsedCliArgs, CliError, VERSION
- src/config.ts: Config type, DEFAULT_CONFIG, resolveConfig
- src/keeper.ts: synthetic-activity sweep + idle-watch loop
- package.json bin entry + shebang for 'bun link' global install
- install.sh: contributor bootstrap (will be repurposed; see
  DISTRIBUTION-PLAN.md for the end-user installer design)
- DISTRIBUTION-PLAN.md captures the tabled end-user distribution work

src/move.ts

@@ -0,0 +1,57 @@
+#!/usr/bin/env bun
+/**
+ * move.ts
+ * -------
+ * Entry point for the `move` CLI.
+ *
+ * Thin shim that ties the three logic modules together:
+ *   - `cli.ts`     parses and validates `process.argv`.
+ *   - `config.ts`  holds the default tunables and the `resolveConfig` overlay.
+ *   - `keeper.ts`  owns the synthetic-activity sweep and idle-watch loop.
+ *
+ * Order of operations:
+ *   1. Parse CLI args. Bad input -> stderr message + short usage hint, exit 2.
+ *   2. `--help` / `--version` short-circuit before any mouse work happens.
+ *   3. Resolve CLI overrides on top of `DEFAULT_CONFIG` and hand the result
+ *      (plus the verbose flag) to `runKeeper`.
+ *   4. Any unhandled rejection from `runKeeper` is logged and exits with
+ *      code 1 so it's catchable by shells / supervisors.
+ *
+ * Runtime: Bun (uses `@nut-tree-fork/nut-js` via `keeper.ts`). The shebang
+ * above lets this file run as a real CLI once linked via `bun link`.
+ */
+
+import { parseCliArgs, printHelp, VERSION } from "./cli.ts";
+import type { ParsedCliArgs } from "./cli.ts";
+import { resolveConfig } from "./config.ts";
+import { runKeeper } from "./keeper.ts";
+
+let cliArgs: ParsedCliArgs;
+try {
+    cliArgs = parseCliArgs();
+} catch (err: unknown) {
+    const msg: string = err instanceof Error ? err.message : String(err);
+    process.stderr.write(`move: ${msg}\nTry 'move --help' for more information.\n`);
+    process.exit(2);
+}
+
+if (cliArgs.help) {
+    printHelp();
+    process.exit(0);
+}
+if (cliArgs.version) {
+    process.stdout.write(`move ${VERSION}\n`);
+    process.exit(0);
+}
+
+const config = resolveConfig({
+    moveInterval: cliArgs.moveInterval,
+    checkInterval: cliArgs.checkInterval,
+    stepDelay: cliArgs.stepDelay,
+    stepCount: cliArgs.stepCount,
+});
+
+runKeeper(config, cliArgs.verbose).catch((err: unknown): void => {
+    console.error("Error:", err);
+    process.exit(1);
+});