docs: fix installation and API guidance

[Teingi]

Which issue or RFC does this PR close?

No linked issue.

Rationale for this change

Current user guides contain a few copy-paste and reference gaps: repeated installs from the mutable master ref may not refresh an existing uv tool, the HTTP examples require a curl option unavailable on older supported environments, authenticated browser access is underspecified, and the configuration reference omits several active inference settings. The CLI and RFC contributor links also point at main although this repository uses master.

What changes are included in this PR?

• Use uv tool install --force consistently in current Git-based installation and integration instructions so an existing tool refreshes the selected ref.
• Replace curl --fail-with-body with the more portable curl --fail in the HTTP examples and document authenticated OpenAPI retrieval.
• Explain which web UI routes remain public to render the sign-in form, which requests remain protected, and where the browser stores the token.
• Complete the Server inference configuration table with generation request limits and embedding model, profile, dimension, normalization, timeout, and batch settings.
• Correct documentation and RFC branch links from main to master in both English and Chinese guidance.

No OpenAPI schema, public API, persistence format, or runtime behavior changes are included.

Are there any user-facing changes?

Yes. Installation, deployment, HTTP API, configuration, tutorial, RFC contributor, and integration documentation is clearer and copy-paste compatible. The CLI help now links to the existing documentation branch. There are no breaking changes.

How was this change tested?

• make docs-test
• make check
• make contract-test (29 passed)
• uv run pytest tests/test_server.py tests/test_dashboard.py tests/test_server_embedding.py tests/test_api_contract.py tests/test_config_cli.py tests/test_docker_contract.py -q (95 passed)
• make test (950 passed, 9 skipped)
• Isolated uv tool install --force "powercontext[cli,server] @ git+https://github.com/oceanbase/powercontext.git@master" from the current upstream commit
• Real local Server checks for unauthenticated Memory remember/search, served OpenAPI, authenticated API rejection/acceptance, and public Dashboard sign-in shell behavior

AI usage statement

OpenAI Codex (GPT-5) was used to audit the documentation against the CLI, Server settings, authentication middleware, OpenAPI contract, and runnable installation/API flows; draft the bilingual updates; and run the validation commands. The changes were reviewed against the repository diff before submission.