style(deps): migrated from Prettier to Biome and updated formatting rules

- Removed Prettier configuration files (.prettierignore and .prettierrc) and migrated formatting to Biome.
- Updated Biome configuration from version 2.3.11 to 2.3.12 and changed arrowParentheses rule from 'always' to 'asNeeded'.
- Pinned @biomejs/biome dependency to exact version 2.3.12 in package.json and bun.lock.
- Applied consistent arrow function formatting across 489 files by removing unnecessary parentheses around single parameters.
- Removed blank lines after comment blocks and reorganized imports for consistency across the codebase.

packages/coding-agent/src/exec/bash-executor.ts

@@ -3,7 +3,6 @@
  *
  * Provides unified bash execution for AgentSession.executeBash() and direct calls.
  */
-
 import { cspawn, Exception, ptree } from "@oh-my-pi/pi-utils";
 import { OutputSink } from "../session/streaming-output";
 import { getShellConfig } from "../utils/shell";