refactor: remove obsolete resource download and installer endpoints

- Deleted the `POST /resources/get/{dataFolder?}` and `GET /resources/get-installer` endpoints as part of the architectural shift towards simplified resource management.
- Removed associated methods and configurations, including `ResourcesService.GetEncryptedResource`, `ResourcesService.GetInstaller`, and related properties in `ResourcesConfig`.
- Cleaned up environment variables and configuration files to reflect the removal of installer-related settings.
- Eliminated the `GetResourceRequest` DTO and its validator, along with the `WrongResourceName` error code.
- Updated documentation to clarify the changes in resource handling and the retirement of per-user file encryption.

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/LESSONS.md

@@ -0,0 +1,19 @@
+# Lessons Log
+
+A ring buffer of the last 15 actionable lessons extracted from retrospectives and incidents.
+Downstream skills consume this file:
+- `.cursor/skills/new-task/SKILL.md` (Step 2 Complexity Assessment)
+- `.cursor/skills/plan/steps/06_work-item-epics.md` (epic sizing)
+- `.cursor/skills/decompose/SKILL.md` (Step 2 task complexity)
+- `.cursor/skills/autodev/SKILL.md` (Execution Loop step 0 — surface top 3 lessons)
+
+Categories: estimation · architecture · testing · dependencies · tooling · process
+
+---
+
+- [2026-05-13] [process] Add a threat-model micro-check to `new-task` Step 5 — endpoints that expose persisted secrets or introduce new auth surface must be flagged at planning, not after a security audit (AZ-183 plaintext-key revert).
+  Source: _docs/06_metrics/retro_2026-05-13.md
+- [2026-05-13] [tooling] Switch batch and review filenames to `batch_NN_cycleM_*.md` starting cycle 2 — the current `batch_NN_*.md` collides on the next cycle and silently overwrites prior history.
+  Source: _docs/06_metrics/retro_2026-05-13.md
+- [2026-05-13] [process] File deploy-skill carry-forward drifts (I, J, K, L, M, N, O) as Jira tickets at the end of every Deploy step so operational debt stays visible and sized.
+  Source: _docs/06_metrics/retro_2026-05-13.md