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/compaction-thinking-model.test.ts

@@ -15,12 +15,12 @@ import { join } from "node:path";
 import { Agent, type ThinkingLevel } from "@oh-my-pi/pi-agent-core";
 import { getModel, type Model } from "@oh-my-pi/pi-ai";
 import { nanoid } from "nanoid";
-import { AgentSession } from "$c/core/agent-session";
-import { AuthStorage } from "$c/core/auth-storage";
-import { ModelRegistry } from "$c/core/model-registry";
-import { SessionManager } from "$c/core/session-manager";
-import { SettingsManager } from "$c/core/settings-manager";
-import { createTools, type ToolSession } from "$c/core/tools/index";
+import { ModelRegistry } from "$c/config/model-registry";
+import { SettingsManager } from "$c/config/settings-manager";
+import { AgentSession } from "$c/session/agent-session";
+import { AuthStorage } from "$c/session/auth-storage";
+import { SessionManager } from "$c/session/session-manager";
+import { createTools, type ToolSession } from "$c/tools/index";
 import { API_KEY } from "./utilities";
 
 // Check for auth