Initial commit: opencode_bridge JupyterLab extension (Slices 1-3.5)

A JupyterLab extension that bridges the cell UI to a local OpenCode Serve
process. The extension is a dual package: a Python server extension
exposed under /opencode-bridge/*, plus a TypeScript frontend that
registers per-cell toolbars.

Backend (Python, tornado)
- Slice 1: config + auth + OpenCode HTTP client (tornado.httpclient,
  no aiohttp). 4 settings in schema/plugin.json (url, user, password,
  request timeout).
- Slice 2: handlers for /hello, /health, /providers, /edit.
- Slice 2.1 (correction): SessionManager with 1 notebook = 1 session
  mapping, async-safe via per-path locks, 404 recovery via invalidate().
  Two new endpoints: GET /sessions, DELETE /session?notebook=<path>.
- 32 pytest tests pass.

Frontend (TypeScript, JupyterLab 4.6)
- src/types.ts: CellContext, OpenCodeRequest/Response, OpenCodeSettings.
- src/context/cell_context.ts: extract CellContext from a CodeCell +
  its parent NotebookPanel, structured error collection.
- src/api/opencode_client.ts: callOpenCodeEdit, callOpenCodeProviders.
- src/components/opencode_cell_footer.ts: OpenCodeCellFooter Widget
  implementing ICellFooter with 3 buttons (optimize / fix / edit),
  resolved via this.parent instanceof CodeCell. NOT cellToolbar
  (does not exist in JL 4.6) and NOT Widget.findParent (removed in
  @lumino/widgets 2.x).
- src/components/opencode_cell_factory.ts: Cell.ContentFactory
  subclass returning the OpenCodeCellFooter.
- src/components/opencode_installer.ts: installOpenCodeEverywhere
  patches every notebook (existing + new) to use the custom factory.
- src/index.ts: registers the factory, loads settings, fetches
  /providers on activation and logs the list to the console.
- 23 jest tests pass (mocked JupyterLab boundary, pnpm path safe).

Settings
- 6 fields: 3 auth (url/user/password) + 1 timeout + 2 model selection
  (provider/model). Provider list is fetched at startup from
  /opencode-bridge/providers and printed to the browser console so
  users can copy values into Settings Editor.

Docs
- design.md: 6 sections covering architecture, UI flow, API contract,
  TS skeletons, session management (v0.2.1 correction), and
  provider/model selection (v0.2.2 addition).
- CLAUDE.md: agent guidance for working in this repo.
- TODO.md: remaining work for Slices 4-7 + v0.4+ backlog.

CI
- Gitea release workflow at .github/workflows/build.yml.
- Bark notification helper (non-fatal on failure).

Generated artefacts ignored: opencode_bridge/labextension/, _version.py,
*.tsbuildinfo, junit.xml, test.ipynb scratch notebook.

eslint.config.mjs

@@ -0,0 +1,68 @@
+import js from '@eslint/js';
+import { defineConfig } from 'eslint/config';
+import tseslint from 'typescript-eslint';
+import prettierRecommended from 'eslint-plugin-prettier/recommended';
+import globals from 'globals';
+import jupyterPlugin from '@jupyter/eslint-plugin';
+
+export default defineConfig([
+  {
+    ignores: [
+      'node_modules',
+      'dist',
+      'coverage',
+      '**/*.js',
+      '**/*.d.ts',
+      '.venv',
+      'tests',
+      '**/__tests__',
+      'ui-tests'
+    ]
+  },
+  js.configs.recommended,
+  tseslint.configs.recommended,
+  jupyterPlugin.configs.recommended,
+  {
+    files: ['**/*.ts', '**/*.tsx'],
+    plugins: {
+      jupyter: jupyterPlugin
+    },
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+        ...globals.es2015,
+        ...globals.node
+      },
+      parserOptions: {
+        project: 'tsconfig.json',
+        sourceType: 'module'
+      }
+    },
+    rules: {
+      '@typescript-eslint/naming-convention': [
+        'error',
+        {
+          selector: 'interface',
+          format: ['PascalCase'],
+          custom: {
+            regex: '^I[A-Z]',
+            match: true
+          }
+        }
+      ],
+      '@typescript-eslint/no-unused-vars': ['warn', { args: 'none' }],
+      '@typescript-eslint/no-explicit-any': 'off',
+      '@typescript-eslint/no-namespace': 'off',
+      '@typescript-eslint/no-use-before-define': 'off',
+      '@typescript-eslint/quotes': [
+        'error',
+        'single',
+        { avoidEscape: true, allowTemplateLiterals: false }
+      ],
+      curly: ['error', 'all'],
+      eqeqeq: 'error',
+      'prefer-arrow-callback': 'error'
+    }
+  },
+  prettierRecommended
+]);