init(config): add initial configuration files

README.md

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+# X Bookmarks → RSS
+
+A tiny [Hono](https://hono.dev) app on Cloudflare Workers that turns your X (Twitter)
+bookmarks into a live RSS 2.0 feed. Uses the official X API v2 (OAuth 2.0 user context).
+State lives in a single **D1** database.
+
+Personal/single-user: the feed is unguarded (`/feed.xml`, no key). Bookmarks are stored in
+D1 and accumulate, so tweets stay in your feed even after they scroll out of X's 100-item
+bookmarks API window.
+
+## How it works
+
+- There is **no login route**. You seed one OAuth2 refresh token into D1 once; from then on
+  the app refreshes the access token itself on every sync (refresh tokens rotate and the new
+  one is written straight back to D1).
+- `GET /feed.xml` — if the last sync is older than `SYNC_TTL_SECONDS`, it refreshes the
+  access token, pages through your bookmarks, and upserts them into D1; then it renders RSS
+  from **all** stored rows (newest first). Sync failures are swallowed — the feed still
+  serves what's already stored.
+
+## Setup
+
+### 1. Create the D1 database
+
+```sh
+npm install
+wrangler d1 create x-bookmarks-db   # paste the printed database_id into wrangler.jsonc
+npm run db:init                      # applies schema.sql to the remote DB
+```
+
+### 2. Set secrets (used to refresh the token)
+
+```sh
+wrangler secret put X_CLIENT_ID
+wrangler secret put X_CLIENT_SECRET
+```
+
+`SYNC_TTL_SECONDS` (default 900) and `MAX_ITEMS` (default 100, items pulled per sync) are
+plain vars in `wrangler.jsonc`.
+
+### 3. Seed your refresh token
+
+You need one OAuth2 refresh token with the `tweet.read users.read bookmark.read
+offline.access` scopes (this is the only step that requires a one-time authorization — every
+sync afterward is automatic). Once you have it:
+
+```sh
+export X_CLIENT_ID=...        # same values as the secrets above
+export X_CLIENT_SECRET=...
+scripts/seed-token.sh "<your-refresh-token>"
+```
+
+The script validates the token, captures the rotated token, and writes `refresh_token` +
+`user_id` into the D1 `meta` table.
+
+### 4. Deploy & subscribe
+
+```sh
+wrangler deploy
+```
+
+Add `https://<your-worker>.workers.dev/feed.xml` to your RSS reader.
+
+## Notes
+
+- Refresh tokens rotate on every use and are written back to D1 immediately.
+- If syncs start failing (token revoked), re-run `scripts/seed-token.sh` with a fresh token.
+- The feed is unguarded by design (personal use). Don't host it where you'd mind it being
+  readable, or re-add a key check.