docs: fix outdated and incorrect references

[dgageot]

A handful of doc pages had drifted away from the code. This PR realigns them with the current behavior. No code changes — docs only.

What's fixed

File	Issue	Fix
docs/tools/tasks/index.md	Tasks tool was documented with the wrong storage backend, default path, and tool names	The tasks tool stores tasks in a JSON file (not SQLite), defaults to ./tasks.json relative to the config dir (not ~/.cagent/tasks.db), and exposes create_task / get_task / update_task / delete_task / list_tasks / next_task / add_dependency / remove_dependency. The old doc only listed four tools and the wrong name add_task (vs. actual create_task). Also documents priorities and dependencies.
docs/providers/openai/index.md	Mentioned a non-existent --gateway CLI flag	The WebSocket transport falls back to SSE when --models-gateway is set (the actual flag, defined in cmd/root/flags.go).
docs/configuration/models/index.md	temperature range listed as 0.0–1.0; frequency_penalty and presence_penalty listed as 0.0–2.0; provider list cut off mid-sentence	temperature is provider-dependent up to 0.0–2.0 (Anthropic caps at 1.0); penalties run -2.0–2.0; the provider row now lists every alias from pkg/model/provider/aliases.go plus a pointer to named providers. The values now match what docs/providers/custom/index.md already says.
docs/configuration/agents/index.md	Properties Reference table listed a top-level rag: field on agents	Agents don't have a rag field. RAG is attached through toolsets: - type: rag, ref: <name> (see examples/rag.yaml). Row removed; the schema/example block already mentioned the correct way.
docs/community/troubleshooting/index.md	"The path field is only valid for memory toolsets"	path is also valid on the tasks toolset and on the agent-level cache block (per the Path field on Toolset / CacheConfig in pkg/config/latest/types.go).
docs/features/rag/index.md	The chunked-embeddings strategy was shown with a model: field	The actual field is embedding_model: — matches every example under examples/rag/*.yaml and the parameter name read by pkg/rag/strategy/chunked_embeddings.go. Fixed in three code blocks and the reference table.

Verification

• temperature / top_p / penalty ranges cross-checked with docs/providers/custom/index.md (which already had the correct ranges) and OpenAI's API reference.
• Tasks tool surface verified against pkg/tools/builtin/tasks.go (registered tool names) and pkg/teamloader/registry.go (default path = tasks.json).
• --models-gateway flag verified in cmd/root/flags.go.
• embedding_model field verified in pkg/rag/strategy/chunked_embeddings.go and examples/rag/{hybrid,custom_provider,reranking,semantic_embeddings}.yaml.
• RAG-via-toolset usage confirmed in examples/rag.yaml.

[docker-agent]

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