Extract WEB UI and TUI into separate packages (in the spirit of tg_shared) #1720

Goal

Extract WEB UI and TUI from the monolith into separate modules/packages following the packages/tg_shared pattern (wave A: #1690): the core stays automation-first, the human-facing surfaces become optional packages.

Motivation

• The automation-first contract: web/TUI are not the primary consumption path, but their code lives in the core and pulls dependencies.
• The tg_shared precedent: extracting application subsystems into packages/* already happened without losing tests or parity.
• Independent evolution and installation: a core without FastAPI/templates and TUI dependencies when the surfaces are not needed.

Scope (a sketch — refine with an audit before implementing)

• Establish the actual boundaries: what from src/web (routes, templates, bootstrap, runtime_shims) moves into the package, what stays as a thin bootstrap.
• TUI likewise — a separate package.
• Entry points (serve, launching the TUI) keep their behavior; the web/worker runtime split (Telegram Worker Decoupling Plan #444/Сбор сообщений молча перестал работать после #444 (воркер-процесс не запускается автоматически) #457) is unchanged.
• Dependencies move into the packages: the core does not pull them when the surfaces are not installed.

Acceptance

• serve and the TUI work as before (a real run, not only unit tests).
• Import contracts (.importlinter) updated and green.
• Surface tests move with the code, the full suite is green.
• The core imports and runs without the web/TUI packages installed.

Note: before starting, the implementer verifies actuality (not a duplicate, what really lives in src/web) and strikes out the stale parts.