F-002 fix: Remove secrets and externalize config

spec/sdd/architecture.md

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+# Architecture Overview — Legacy PHP Product Module
+
+## Context
+This repo holds one legacy PHP module copied from production.
+The module helps product staff create products and generate SEO text.
+The module also runs one batch worker that updates OpenCart product descriptions.
+
+Current raw source path was `project/new`.
+Target stable path is `project/web/index/new`.
+SQL dump target path is `project/sql/db-25052026.sql`.
+
+## Main flows
+1. User opens product form.
+2. Form reads OpenCart data from MariaDB.
+3. User can open AI helper page for one product text.
+4. Bulk page writes product ids into `oc_product_queue`.
+5. CLI worker reads queue, calls OpenAI, updates `oc_product_description`.
+
+## Constraints
+- Keep legacy behavior unchanged in layout and config features.
+- Preserve file contents during move unless config externalization requires value lookup changes.
+- Keep evidence in repo for each design change.
+- Do not redesign auth or deploy in these features.
+
+## System view
+```mermaid
+graph TD
+    U[Backoffice user] --> F[Legacy PHP web module]
+    F --> DB[(MariaDB / OpenCart)]
+    F --> Q[oc_product_queue]
+    W[worker_bulk.php CLI worker] --> Q
+    W --> AI[OpenAI API]
+    W --> DB
+```
+
+## Files and responsibilities
+- `bootstrap.php`: shared local config loader and DB helper
+- `config/local.example.php`: versioned config shape
+- `config/local.php`: ignored local values file
+- `index.php`: manual product create form
+- `describe.php`: one-shot AI description helper
+- `productos_bulk_update.php`: queue intake and worker log viewer
+- `productos_modificados.php`: review processed items
+- `worker_bulk.php`: batch generator and DB updater
+- `inc/*`: shared layout, prompts, AJAX helpers
+- `db/conn.php`: shared DB connection for web pages
+- `logs/*`: runtime debug output from worker and AI calls