docs: update environment configuration and API documentation

- Revised the `.env.example` file to clarify the purpose of the `MINI_APP_SKIP_AUTH` variable, emphasizing its insecure nature and restriction to development use only.
- Updated the `README.md` to reflect changes in API authentication requirements, specifying that unauthenticated access to `/api/duties` and `/api/calendar-events` is only allowed with `MINI_APP_SKIP_AUTH=1`.
- Enhanced `configuration.md` to detail the implications of using `MINI_APP_SKIP_AUTH` for API access without Telegram initData.
- Removed the `_is_private_client` function and its associated tests, streamlining the codebase and focusing on the current authentication model.
- Added logging in `run.py` to warn when `MINI_APP_SKIP_AUTH` is enabled, highlighting the security risks.

docs/configuration.md

@@ -12,7 +12,7 @@ All configuration is read from the environment (e.g. `.env` via python-dotenv).
 | **ADMIN_USERNAMES** | comma-separated list | *(empty)* | Telegram usernames treated as **admin fallback** when the user has **no role in the DB**. If a user has a role in the DB, only that role applies. Example: `admin1,admin2`. |
 | **ALLOWED_PHONES** | comma-separated list | *(empty)* | **Not used for access.** Kept for reference only. |
 | **ADMIN_PHONES** | comma-separated list | *(empty)* | Phones treated as **admin fallback** when the user has **no role in the DB** (user sets phone via `/set_phone`). Comparison uses digits only. Example: `+7 999 123-45-67`. |
-| **MINI_APP_SKIP_AUTH** | `1`, `true`, or `yes` | *(unset)* | If set, `/api/duties` is allowed without Telegram initData (dev only; insecure). |
+| **MINI_APP_SKIP_AUTH** | `1`, `true`, or `yes` | *(unset)* | If set, `/api/duties` and `/api/calendar-events` are allowed without Telegram initData. **Dev only — never use in production.** |
 | **INIT_DATA_MAX_AGE_SECONDS** | integer | `0` | Reject Telegram initData older than this many seconds. `0` = disabled. Example: `86400` for 24 hours. |
 | **CORS_ORIGINS** | comma-separated list | `*` | Allowed origins for CORS. Leave unset or set to `*` for allow-all. Example: `https://your-domain.com`. |
 | **EXTERNAL_CALENDAR_ICS_URL** | string (URL) | *(empty)* | URL of a public ICS calendar (e.g. holidays). If set, those days are highlighted on the duty grid; users can tap "i" on a cell to see the event summary. Empty = no external calendar. |

docs/runbook.md

@@ -48,13 +48,13 @@ On container start, `entrypoint.sh` runs Alembic migrations then starts the app
 
 ### Miniapp "Open in browser" or direct link — access denied
 
-- **Cause:** When users open the calendar via “Open in browser” or a direct URL, Telegram may not send `tgWebAppData` (initData). The API requires initData (or `MINI_APP_SKIP_AUTH` / private IP in dev).
+- **Cause:** When users open the calendar via “Open in browser” or a direct URL, Telegram may not send `tgWebAppData` (initData). The API requires initData (or `MINI_APP_SKIP_AUTH` in dev).
 - **Action:** Users should open the calendar **via the bot’s menu button** (e.g. ⋮ → "Calendar") or a **Web App inline button** so Telegram sends user data.
 
 ### 403 "Open from Telegram" / no initData
 
-- **Cause:** Request to `/api/duties` (or calendar) without valid `X-Telegram-Init-Data` header. In production, only private IP clients can be allowed without initData (see `_is_private_client` in `api/dependencies.py`); behind a reverse proxy, `request.client.host` is often the proxy (e.g. 127.0.0.1), so the “private IP” bypass may not apply to the real user.
-- **Check:** Ensure the Mini App is opened from Telegram (menu or inline button). If behind a reverse proxy, see README “Production behind a reverse proxy” (forward real client IP or rely on initData).
+- **Cause:** Request to `/api/duties` or `/api/calendar-events` without valid `X-Telegram-Init-Data` header. The API returns 403 without initData; the only bypass is `MINI_APP_SKIP_AUTH=1` (dev only, insecure).
+- **Check:** Ensure the Mini App is opened from Telegram (menu or inline button). For local dev without Telegram, use `MINI_APP_SKIP_AUTH=1` in `.env`.
 
 ### Mini App URL — redirect and broken auth