feat(reader): Gitea client + config + board orchestrator

closes board-viewer-gitea-reader

- src/gitea.ts: HTTP client (getFile, getLatestCommitIso, rawUrl); DI'd fetch
- src/reader.ts: readBoard(client, repos) → TaskRecord[]
- src/config.ts: TOML config loader with board_viewer_repos whitelist
- 25 tests total (9 parser incl. 3 real-repo fixtures, 7 gitea, 5 reader, 4 config)
- emoji contract ⚪🔴🟡🔵🟢 (open/in_progress/paused/blocked/done)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/config.ts

@@ -0,0 +1,50 @@
+import { readFileSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { join } from 'node:path';
+import { parse as parseToml } from 'smol-toml';
+import type { RepoRef } from './reader.ts';
+
+export interface BoardConfig {
+  baseUrl: string;
+  token: string;
+  repos: RepoRef[];
+}
+
+export function defaultConfigPath(): string {
+  return join(homedir(), '.config', 'projects-mcp', 'auth.toml');
+}
+
+export function loadConfig(path: string = defaultConfigPath()): BoardConfig {
+  const raw = readFileSync(path, 'utf8');
+  const data = parseToml(raw) as Record<string, unknown>;
+
+  const baseUrl = stringField(data, 'gitea_url');
+  const token = stringField(data, 'gitea_token');
+  const repos = parseRepos(data['board_viewer_repos']);
+
+  return { baseUrl, token, repos };
+}
+
+function stringField(data: Record<string, unknown>, key: string): string {
+  const value = data[key];
+  if (typeof value !== 'string' || value.length === 0) {
+    throw new Error(`config: missing or empty string field "${key}"`);
+  }
+  return value;
+}
+
+function parseRepos(value: unknown): RepoRef[] {
+  if (!Array.isArray(value)) {
+    throw new Error('config: missing or invalid "board_viewer_repos" (expected array of "owner/repo")');
+  }
+  return value.map((entry) => {
+    if (typeof entry !== 'string') {
+      throw new Error(`config: board_viewer_repos entry must be string, got ${typeof entry}`);
+    }
+    const parts = entry.split('/');
+    if (parts.length !== 2 || parts[0] === '' || parts[1] === '') {
+      throw new Error(`config: board_viewer_repos entry "${entry}" is not "owner/repo"`);
+    }
+    return { owner: parts[0]!, repo: parts[1]! };
+  });
+}