feat: consolidated Gitea API client and pi extension

- Pure fetch-based API client (src/) with zero external dependencies
- Pi extension adapter (pi-extension/) registering 17 tools
- Standalone CLI (cli.ts) replacing gitea-scripts/gitea.js
- Token auth everywhere (no HMAC secrets)
- SKILL.md for agent auto-discovery
- TOOL.md with full parameter reference

Consolidates pi-bot/extensions/pi-gitea and clawbot/gitea-scripts
into a single shared package.

src/files.ts

@@ -0,0 +1,91 @@
+/**
+ * File / content operations
+ */
+
+import type { GiteaClient } from "./client.js";
+
+export interface FileContent {
+	name: string;
+	path: string;
+	sha: string;
+	content: string;
+	encoding: string;
+	size: number;
+	html_url: string;
+}
+
+export interface FileCommitResponse {
+	content: FileContent;
+	commit: { sha: string; html_url: string };
+}
+
+export interface Branch {
+	name: string;
+	commit: { id: string; message: string };
+}
+
+/** Get file content from a repo */
+export async function getFileContent(
+	client: GiteaClient,
+	owner: string,
+	repo: string,
+	filepath: string,
+	opts: { ref?: string } = {},
+): Promise<FileContent> {
+	const ref = opts.ref ? `?ref=${encodeURIComponent(opts.ref)}` : "";
+	return client.get<FileContent>(`/repos/${owner}/${repo}/contents/${filepath}${ref}`);
+}
+
+/** Create or update a file in a repo */
+export async function updateFile(
+	client: GiteaClient,
+	owner: string,
+	repo: string,
+	filepath: string,
+	opts: { content: string; message: string; branch?: string; sha?: string },
+): Promise<FileCommitResponse> {
+	return client.put<FileCommitResponse>(`/repos/${owner}/${repo}/contents/${filepath}`, {
+		content: Buffer.from(opts.content).toString("base64"),
+		message: opts.message,
+		branch: opts.branch,
+		sha: opts.sha,
+	});
+}
+
+/** Delete a file in a repo */
+export async function deleteFile(
+	client: GiteaClient,
+	owner: string,
+	repo: string,
+	filepath: string,
+	opts: { sha: string; message: string; branch?: string },
+): Promise<void> {
+	// Gitea's delete file endpoint uses DELETE with a body
+	await client.request("DELETE", `/repos/${owner}/${repo}/contents/${filepath}`, {
+		sha: opts.sha,
+		message: opts.message,
+		branch: opts.branch,
+	});
+}
+
+/** Create a branch */
+export async function createBranch(
+	client: GiteaClient,
+	owner: string,
+	repo: string,
+	opts: { name: string; oldRef?: string },
+): Promise<Branch> {
+	return client.post<Branch>(`/repos/${owner}/${repo}/branches`, {
+		new_branch_name: opts.name,
+		old_branch_name: opts.oldRef ?? "main",
+	});
+}
+
+/** List branches */
+export async function listBranches(
+	client: GiteaClient,
+	owner: string,
+	repo: string,
+): Promise<Branch[]> {
+	return client.get<Branch[]>(`/repos/${owner}/${repo}/branches`);
+}