docs: fix outdated content and document missing commands

[dgageot]

Spotted while auditing the published documentation against the source.

Wrong / outdated information

• Azure provider env var — the azure alias defaults to AZURE_API_KEY (see pkg/model/provider/aliases.go), not AZURE_OPENAI_API_KEY. Updated the providers overview, the models concept page, and the troubleshooting cheat sheet.
• GitHub Copilot env var — the alias reads GITHUB_TOKEN (a PAT with the copilot scope), not "GitHub CLI auth (gh auth login)". The dedicated providers/github-copilot page already documents this correctly; the overview tables now match.
• Broken internal link — docs/providers/openai/index.md linked to /examples/websocket_transport/, which doesn't exist as a docs page. Linked the YAML on GitHub instead.
• Troubleshooting nits — fixed a stray extra column delimiter in the Log Analysis table that was rendering as a malformed header, and a missing word in the Port conflicts section ("When docker-agent as an API server" → "When running docker-agent as an API server").

Missing content

• Sidebar — Tasks (/tools/tasks/) and Model Picker (/tools/model-picker/) pages exist but were never linked from the Built-in Tools navigation. Added them.
• docker agent serve chat — this command (an OpenAI-compatible Chat Completions server at /v1/chat/completions and /v1/models) was not documented anywhere despite being a real, shipped command. Added a section in the CLI reference with the full flag table and a curl example.
• docker agent version — added a short section in the CLI reference.
• Missing docker agent run flags — surfaced from cmd/root/run.go and cmd/root/flags.go: --remote, --working-dir, --env-from-file, --code-mode-tools, --models-gateway, --fake, --record.
• Global flags — added --cache-dir, --config-dir, --data-dir (from cmd/root/root.go) to the Global Flags table.
• Troubleshooting API-key cheat sheet — rounded it out with Nebius, MiniMax, Requesty, GitHub Copilot, and Azure entries, and noted that GOOGLE_API_KEY and GEMINI_API_KEY are both honored.

Files changed

docs/_data/nav.yml                      |  4 ++
docs/community/troubleshooting/index.md | 27 ++++++++------
docs/concepts/models/index.md           |  4 +-
docs/features/cli/index.md              | 68 +++++++++++++++++++++++++++++++---
docs/providers/openai/index.md          |  2 +-
docs/providers/overview/index.md        |  4 +-
6 files changed, 87 insertions(+), 22 deletions(-)

Docs-only — no Go changes, no behavior changes.

[docker-agent]

Assessment: 🟡 NEEDS ATTENTION

This PR fixes several documentation inaccuracies (Azure/GitHub Copilot env vars, broken link, table formatting) and adds missing documentation for new commands and nav entries. The changes are accurate and well-structured. One minor issue found in the newly added content.

[docker-agent]

[MEDIUM] Hardcoded version number in example will become stale

The docker agent version example uses a specific real version number (v1.54.0) and commit hash (1737035c). These will be outdated as soon as the next release ships, and users may be confused when their actual output differs from the docs.

Consider using placeholder values instead:

$ docker agent version
docker agent version vX.Y.Z
Commit: <commit-hash>