refactor(coding-agent): flattened directory structure, eliminated core/ folder

- Eliminated core/ directory (252 files, 23 subdirs → distributed)
- Reduced max nesting from 9 levels to 5 levels
- Promoted tool subdirs to top level: exa/, lsp/, patch/, task/, web/
- Merged web-scrapers/ + web-search/ into web/{scrapers,search}/
- Flattened modes/interactive/ to modes/
- Split execution/ into: ipy/ (python), exec/ (bash), ssh/
- Renamed ipy/python-*.ts to ipy/*.ts (executor, kernel, etc.)
- Flattened cursor/exec-bridge.ts to cursor.ts
- Created logical groupings: config/, session/, extensibility/, export/
- Updated all imports across 500+ files

packages/coding-agent/test/core/python-modules.test.ts

@@ -2,7 +2,7 @@ import { afterEach, describe, expect, it } from "bun:test";
 import { mkdirSync, readFileSync, writeFileSync } from "node:fs";
 import { basename, join, resolve } from "node:path";
 import { createTempDirSync } from "@oh-my-pi/pi-utils";
-import { discoverPythonModules, loadPythonModules, type PythonModuleExecutor } from "$c/core/python-modules";
+import { discoverPythonModules, loadPythonModules, type PythonModuleExecutor } from "$c/ipy/modules";
 
 const fixturesDir = resolve(import.meta.dir, "../../test/fixtures/python-modules");