docs: cover cuga-agent features added in the last 6 months

[haroldship]

Related Issue

Closes #2

Context

Audit of docs against cuga-project/cuga-agent (README, code, src/cuga/settings.toml, and merged PRs over the last ~6 months) identified several major agent capabilities that had no doc coverage and a number of stale entries. This PR closes the gap. Original audit / gap tracking lived in an internal issue; the full plan is reproduced here.

Summary

8 new pages under content/docs/customization/:

• knowledge.mdx — Docling-powered knowledge base (agent.knowledge, enable_knowledge, cuga start demo_knowledge, scopes, routing through CugaLite).
• context-summarization.mdx — [context_summarization] config, trigger modes, supervisor support.
• evolve.mdx — altk-evolve integration: registry-managed vs standalone SSE, all modes/timeouts.
• storage.mdx — local (sqlite-vec) vs prod (Postgres + pgvector) backends and embedding providers.
• secrets-vault.mdx — Local-env vs HashiCorp Vault (token / Kubernetes auth, KV v1/v2, TLS).
• authentication.mdx — OIDC/BFF auth, role-based authorization, IAM-proxy front-ends, role_token_source.
• observability.mdx — OpenLit/OTLP observability and the local docker-compose stack.
• ui-branding.mdx — hide_cuga_logo, brand_name for white-labelling the demo.

Expanded customization/settings-reference.mdx to mirror the current settings.toml:

• Added full option tables for [supervisor], [storage], [storage.embedding], [policy], [service], [secrets], [auth], [ui], [context_summarization], [connections], [observability], [evolve].
• Filled in every missing [advanced_features] flag (force_lite_mode_apps, cuga_lite_max_steps, cuga_lite_bind_tools_*, cuga_lite_nl_auto_continue, cuga_lite_enable_few_shots, enable_todos, reflection_enabled, tool_call_timeout, execution_output_max_length, sub_task_keep_last_n, code_executor_keep_last_n, path_segment_index, force_autonomous_mode, appworld_final_answer_plain).
• Updated [server_ports] (added filesystem_mcp, docs_mcp, oak_health_api, demo_server_startup_max_retries; removed dead memory = 8888).
• Added env-var subsections for Secrets & Vault, OIDC/BFF, Service Identity, TLS-for-inference, Storage, and Observability.
• Reworked the "Production Enterprise Setup" example to demonstrate [auth] + Vault + Postgres + OpenLit.

SDK updates

• sdk/cuga_agent.mdx — documented the new enable_knowledge constructor parameter (default True), the agent.knowledge property (ingest / search / list_documents, scopes), and the new aclose() resource-cleanup method.
• sdk/cuga_supervisor.mdx — documented cuga start demo_supervisor (CRM + email sub-agents demo).

Deprecation handling

• customization/memory.mdx opens with a Callout explaining that mem0 / enable_memory / enable_fact / the memory server port were removed from CUGA classic in cuga-agent PR #153 (2026-04-23). The body is kept as-is for users still on older versions; the callout links to Evolve / Context Summarization / Knowledge as replacements.
• Stale memory_provider / enable_memory / memory = 8888 lines removed from settings-reference.mdx (config examples, Dynaconf env vars, troubleshooting tips).

Minor errors fixed along the way

• Removed a leftover AI-prompt artifact at the bottom of architecture-section/overview.mdx ("👉 Next step could be to include an inline Mermaid diagram… Want me to add that Mermaid diagram block…?").
• Fixed GENT_SETTING_CONFIG → AGENT_SETTING_CONFIG typo in the Groq section of customization/llm-config.mdx.
• Replaced "Selenium/Playwright" in the Quick Start tech-stack accordion with the accurate "Playwright (with a Chromium-based extension for web/hybrid modes)" — Selenium is not in the current code.

Test plan

• npm run build — all 76 static pages compile (had to swap two ```env fences to ```bash because this repo's Shiki bundle doesn't include env).
• Sidebar shows all 8 new pages under Customization in order: Knowledge, Context Summarization, Evolve, Storage, Secrets & Vault, Authentication, Observability, UI Branding (then Memory, E2B, Settings Reference).
• /docs/customization/memory shows the deprecation callout at the top.
• /docs/customization/settings-reference includes the 11 new section headings.
• /docs/sdk/cuga_agent shows enable_knowledge in the parameters TypeTable and the new ### knowledge / ### aclose sections.
• /docs/sdk/cuga_supervisor includes the Try the Demo block with cuga start demo_supervisor.
• /docs/architecture-section/overview ends cleanly at the "Performance Monitoring" bullet (no AI-prompt artifact).
• /docs/getting-started/installation and /docs/getting-started — Quick Start tech-stack accordion no longer mentions Selenium.
• /docs/customization/llm-config — Groq snippet shows AGENT_SETTING_CONFIG.