SK-2707: drop .env.example from samples, document placeholder workflow

Remove samples/.env.example and the dotenv/.env loading guidance from
samples/README.md. The samples are run by replacing the inline
<PLACEHOLDER> values directly. Update the OB-11 backlog entry to match.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Devesh-Skyflow

docs/onboarding-backlog.md

@@ -39,7 +39,7 @@ Evidence tagging: claims verified against code carry a `file:line` reference. It
 | OB-8 | Document undocumented enums (TokenMode, etc.) | README-content | P1 | S | API-coverage |
 | OB-9 | Document Skyflow client-management methods | README-content | P1 | S | API-coverage |
 | OB-10 | Document `is_expired` & `generate_signed_data_tokens_from_creds` | README-content | P1 | S | API-coverage |
-| OB-11 | Add `samples/README.md` + `.env.example` | Samples | P1 | M | Onboarding |
+| OB-11 | Add `samples/README.md` | Samples | P1 | M | Onboarding |
 | OB-12 | Document client lifecycle / thread-safety / retries | README-content | P1 | M | Onboarding |
 | OB-13 | Document Detect helper classes (EntityInfo, TextIndex, Bleep, File) | README-content | P2 | M | API-coverage |
 | OB-14 | Add README badges (PyPI, Python versions, build, license) | Polish | P2 | S | Onboarding |
@@ -164,14 +164,14 @@ Evidence tagging: claims verified against code carry a `file:line` reference. It
 
 **Acceptance criteria:** Both functions documented with a usage snippet.
 
-### OB-11 · `samples/README.md` + `.env.example`
+### OB-11 · `samples/README.md`
 *Priority P1 · Effort M · Samples · Onboarding*
 
-**Problem:** 22 sample files across `samples/{vault_api,detect_api,service_account}` have no README and no env template; each hardcodes `<PLACEHOLDERS>`. There's no `cp .env.example .env` flow to make them runnable.
+**Problem:** 22 sample files across `samples/{vault_api,detect_api,service_account}` have no README explaining prerequisites or how to run them; each hardcodes `<PLACEHOLDERS>`.
 
-**Proposed fix:** Add `samples/README.md` (prerequisites, how to run, what each sample shows) and a `.env.example` with the variables the samples read. Optionally refactor samples to load from env.
+**Proposed fix:** Add `samples/README.md` (prerequisites, how to run, what each sample shows, per-sample index).
 
-**Acceptance criteria:** A user can run any sample by copying `.env.example`, filling values, and following `samples/README.md`.
+**Acceptance criteria:** A user can run any sample by following `samples/README.md` and replacing the inline placeholders with their own values.
 
 ### OB-12 · Client lifecycle / thread-safety / retries
 *Priority P1 · Effort M · README-content · Onboarding*

samples/.env.example

@@ -7,31 +7,13 @@ Runnable examples for the Skyflow Python SDK, grouped by area. Start with the [R
 - Python 3.9 or above
 - The SDK installed: `pip install skyflow`
 - A Skyflow account, a vault, and a service account (see [Before you begin](../README.md#before-you-begin))
-- The values listed in [`.env.example`](.env.example): `vault_id`, `cluster_id`, `env`, and one credential (API key, bearer token, or service-account credentials)
+- Your `vault_id`, `cluster_id`, `env`, and one credential (API key, bearer token, or service-account credentials)
 
 ## Configure
 
-Copy the env template and fill in your values:
+The samples ship with inline `<PLACEHOLDER>` strings (for example `<YOUR_VAULT_ID>`). Replace the placeholders in the sample you want to run with your own values before running it.
 
-```bash
-cp .env.example .env
-```
-
-The samples ship with inline `<PLACEHOLDER>` strings (for example `<YOUR_VAULT_ID>`). You can either:
-
-1. **Replace the placeholders** directly in the sample file you want to run, or
-2. **Load from `.env`** by adding the following near the top of the sample (`python-dotenv` is already a SDK dependency):
-
-   ```python
-   import os
-   from dotenv import load_dotenv
-
-   load_dotenv()
-   vault_id = os.getenv('SKYFLOW_VAULT_ID')
-   # ...use os.getenv(...) for the other values
-   ```
-
-> Never commit a filled-in `.env` or any real credentials.
+> Never commit real credentials.
 
 ## Run a sample