Data source: Redis plugin

In-memory key-value store. **Non-SQL** — key browser + command console.

Builds on the **Seshat** foundation (#93, shipped in #99): host `tcp-client` (+ host-side TLS), owner-thread query execution, `secure-storage` for credentials, and the `UiNode` DSL (connection dialog, dock tabs, results grid, `json-tree`).

## Transport
- RESP protocol over TCP `:6379` (simple to implement). Auth: `AUTH` password (+ optional ACL user), TLS.

## Reuse
- `tcp-client`, owner thread, `secure-storage`, tabs.

## New work
- RESP codec; a key browser (`SCAN` with pattern + `TYPE`), type-aware value views (string / hash / list / set / zset / stream); a command console; DB-index switcher.

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Part of the data-source plugins epic #109.