feat(proxy): add scoped proxy configuration and docs runbooks

- add scope-aware proxy schema and runtime wiring for providers/channels/tools

- add agent callable proxy_config tool for fast proxy setup

- standardize docs system with index, template, and playbooks

docs/doc-template.md

@@ -0,0 +1,63 @@
+# Documentation Template (Operational)
+
+Use this template when adding a new operational or engineering document under `docs/`.
+
+Keep sections that apply; remove non-applicable placeholders before merging.
+
+---
+
+## 1. Summary
+
+- **Purpose:** <one sentence about why this document exists>
+- **Audience:** <operators | reviewers | contributors | maintainers>
+- **Scope:** <what this doc covers>
+- **Non-goals:** <what this doc intentionally does not cover>
+
+## 2. Prerequisites
+
+- <required environment>
+- <required permissions>
+- <required tools/config>
+
+## 3. Procedure
+
+### 3.1 Baseline Check
+
+1. <step>
+2. <step>
+
+### 3.2 Main Workflow
+
+1. <step>
+2. <step>
+3. <step>
+
+### 3.3 Verification
+
+- <expected output or success signal>
+- <validation command/log/checkpoint>
+
+## 4. Safety, Risk, and Rollback
+
+- **Risk surface:** <which components may be impacted>
+- **Failure modes:** <what can go wrong>
+- **Rollback plan:** <concrete rollback command/steps>
+
+## 5. Troubleshooting
+
+- **Symptom:** <error/signal>
+  - **Cause:** <likely cause>
+  - **Fix:** <action>
+
+## 6. Related Docs
+
+- [README.md](./README.md) — documentation taxonomy and navigation.
+- <related-doc-1.md>
+- <related-doc-2.md>
+
+## 7. Maintenance Notes
+
+- **Owner:** <team/persona/area>
+- **Update trigger:** <what changes should force this doc update>
+- **Last reviewed:** <YYYY-MM-DD>
+