fix: six small fixes from the work log

[caioricciuti]

Six small fixes from WORK_LOG §0.1 item 3 (including 4.19 and 4.20). No schema or dependency change.

1. Audit Log shows the ClickHouse user. ch_user was stored and returned by the API but missing on the page, in the CSV export and in SIEM events. Now a "ClickHouse user" column and detail row, a ch_user CSV column, and ch_user on forwarded events (stdout, file, webhook). Same rule as storage: only when it differs from the actor.
2. DELETE /api/history/{id} answers 404 when the entry is not the caller's (or does not exist). It already deleted nothing; it just said 200.
3. ClickHouse user password and delete endpoints decode {username}, as the role routes do. Names with @ or : failed, and the delete self-guard compared the escaped name.
4. Login says "Connector online / offline" instead of "Connected / Unreachable". The flag is the connector tunnel; ClickHouse is checked at sign-in (4.19).
5. /settings redirects to /license, keeping ?section=, so old links open the License page instead of home (4.20).
6. Telemetry shows setup help when the OTel tables are missing (ClickHouse 60 UNKNOWN_TABLE, 81 UNKNOWN_DATABASE, or an empty DESCRIBE) instead of the raw error, in Logs, Traces and Metrics.

Docs: audit-log, monitoring (SIEM event) and cant-login pages updated.

Checked

make vet test passes; bun run check 0 errors; bun run test 103 passed (new isMissingTableError tests); site builds. Two existing tests that asserted the old 200 on a foreign history delete now expect not found.

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