refactor: migrate adapter imports to package exports

[jackwener]

Summary

Replaces all relative imports across 484 adapter files with Node.js package exports (@jackwener/opencli/registry, @jackwener/opencli/errors, etc.).

Before: adapters used fragile relative paths (../../src/registry.js) that broke whenever the internal directory structure changed (caused #788, #791).

After: adapters use stable package exports that resolve through Node.js module resolution, completely decoupled from internal layout.

What changed

• package.json: added 14 sub-path exports covering all public modules
• 484 adapter files: ../../src/registry.js → @jackwener/opencli/registry, etc.
• discovery.ts: simplified ensureUserCliCompatShims from ~80 lines of shim generation to ~30 lines (just symlink + package.json)
• registry-api.ts: exported CommandArgs type (was missing)
• Removed: root-level shim directories (browser/, download/, pipeline/) and their tsconfig/package.json entries

User adapter authoring (new pattern)

import { cli, Strategy } from '@jackwener/opencli/registry';
import { CliError } from '@jackwener/opencli/errors';
import type { IPage } from '@jackwener/opencli/types';

Works in both ~/.opencli/clis/ (via symlink) and the package itself (via self-referencing).

Test plan

• Build succeeds (497 entries manifest)
• All 496 unit tests pass (42 files)
• Compiled adapters use @jackwener/opencli/... imports

[Astro-Han]

设计很干净。package exports + self-referencing 是正解，也为后续 monorepo 迁移铺好了路。

提一个加固建议：shim 移除后，symlink 成了用户 CLI 解析的唯一通道。当前如果 symlink 位置已经是普通目录而非 symlink，unlink() 删不掉目录，symlink() 因 EEXIST 失败，外层 catch 静默吞掉异常，用户侧无任何提示。

建议把 unlink 换成 rm：

try { await fs.promises.rm(symlinkPath, { recursive: true, force: true }); } catch { /* doesn't exist */ }

外层 catch 也值得加一行 console.warn，方便排障。

[jackwener]

Thanks for the review! Both suggestions applied:

1. unlink() → rm({ recursive: true, force: true }) — handles stale directories that unlink can't remove
2. Outer catch now logs a warning via log.warn() instead of silently swallowing the error

Pushed in 4877213.

[Astro-Han]

Post-merge follow-up: the symlink approach has a gap I missed during review.

The symlink at ~/.opencli/node_modules/@jackwener/opencli correctly resolves package exports (@jackwener/opencli/registry, etc.), but adapters also import third-party packages as bare specifiers (chalk, turndown). These resolve by walking up from ~/.opencli/clis/<site>/, which never reaches the global node_modules/ where the actual packages live.

This is now surfacing as the remaining failures in #792 (1.6.5).

Suggested fix: extend ensureUserCliCompatShims to also symlink each dependency from package.json into ~/.opencli/node_modules/, derived from the package root's parent directory (the global modules tree).

Sorry for missing this in the original review.