docs: fix stale defaults, wrong tool names, and missing CLI flags

[dgageot]

A full review of the docs site against the current code turned up a number of claims that were false or out of date. This fixes all of them, verified against the CLI help output, agent-schema.json, and the relevant Go packages.

The biggest offenders were the config version (documented as 8, current is 10), the Anthropic/Bedrock thinking defaults (several pages contradicted each other; per pkg/model/provider/defaults.go, thinking is off unless thinking_budget is set and interleaved_thinking is then auto-enabled for Claude models), and the model-picker page, which documented a pick_model tool that does not exist — the real tools are change_model and revert_model, and the switch is immediate rather than next-turn.

Smaller fixes: the serve a2a --agent default is the team's first agent, not root; the filesystem post-edit hook docs referenced a nonexistent patch_file tool; the RAG pages used batch_size instead of embedding_batch_size and documented wrong defaults for chunk size and reranking top_k; and the CLI/TUI references were missing --theme, --on-event, --tool-name, --mcp-keepalive, --attach, and the /skills command. Docs-only change, no code touched.

[docker-agent]

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