fix: harden debug logging and LLM endpoint validation

[TimInTech]

Security fixes

• Removes arbitrary key-event data from DEBUG logs.
• Rejects public HTTP LLM endpoints while retaining exact localhost, loopback, and RFC1918 IPv4 literals for local HTTP use.
• Clears unsafe legacy endpoint values and presents a visible settings warning.
• Corrects related security, privacy, and support documentation.

Verification

• 571 passed, 2 skipped, 0 failed
• git diff --check clean
• Independent read-only patch review completed; the follow-up URL-parser fix was re-reviewed.

No secrets, raw logs, or sensitive input are included.

[chatgpt-codex-connector]

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