refactor(error): unify structured error handling

[qin-ctx]

Description

Unify OpenViking API, SDK, and CLI error handling around the structured code, message, and optional details contract. Remove CLI/server message-text classification, preserve unknown upstream messages, and fix structured JSON output for CLI runtime errors.

Human Involvement

• A human participated in the implementation or review loop
• This PR was generated entirely by AI agents without human participation in the loop

Related Issue

N/A

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test update

Changes Made

• Add canonical server error codes and exception types, with HTTP mapping at the API boundary.
• Classify known source failures from exception types, status codes, and provider codes; preserve unknown messages instead of parsing their text.
• Remove the CLI error classifier, keep server messages/details intact in SDK and CLI output, and honor --output json for runtime errors.
• Map lock/CAS contention to ABORTED, existing resources to ALREADY_EXISTS, invalid URIs to INVALID_ARGUMENT, and invalid state to FAILED_PRECONDITION.
• Add English/Chinese error-code references plus before/after API and CLI examples.

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have tested this on the following platforms:
  • Linux
  • macOS
  • Windows

Validated locally:

• cargo test -q -p ov_cli — 403 passed.
• Focused Python SDK, Feishu, server mapping, path-lock, and compatibility tests — 93 passed.
• Ruff, rustfmt, and git diff --check passed for the changed error-handling paths.

The broader Python selection is currently blocked by missing watch_manager fixtures and required OpenViking config isolation on the latest main; these failures also affect tests outside this change. The PR is intentionally opened as draft.

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Screenshots (if applicable)

N/A

Additional Notes

This changes outbound public error codes. Deprecated codes such as CONFLICT, INVALID_URI, NOT_INITIALIZED, and SESSION_EXPIRED remain accepted by compatibility clients, but new server responses use the broader canonical codes documented in docs/en/api/12-error-codes.md and docs/zh/api/12-error-codes.md.