[Feat] Add dedicated Telegram bots for existing Sessions

[roomote-roomote]

​Opened on behalf of @daniel-lxs. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

Related issue

No linked issue. Requested continuation of an existing Roomote implementation.

Why this PR exists

• A maintainer explicitly invited this PR in the linked issue or discussion
• I am a maintainer / this is internal Roomote work

Existing private Telegram Sessions can have a dedicated bot without manually copying credentials or creating a second conversation. This recovers the completed implementation and delivers it against current Roomote develop, not Roomote Cloud.

What changed

• Add /sessionbot with Telegram's native Yes, create bot button, explicit bot/Session confirmation, automatic managed-token retrieval and authenticated webhook setup.
• Bind the existing Session through an expiring one-use activation link, with owner-only private-chat authorization and encrypted credentials.
• Route dedicated-bot messages, supported attachments, replies and background task updates through the bound bot. /disconnect stops delivery without deleting Session history or falling back to main-bot credentials.
• Add an additive database migration, regression tests and public setup/limitations documentation.

Initial scope is existing private Telegram Fast Sessions. Groups, arbitrary web Session selection, reconnect, child inline actions/reactions and automatic token/ownership-change recovery are not included. Disconnect does not restore main-bot routing.

How it was tested

• 366 focused tests passed on current source: API 93, communication 45, PostgreSQL lifecycle 16 and SDK 212.
• pnpm lint, pnpm knip, docs build/link validation and local development migration application passed; test schema applied successfully.
• Commit and push hooks passed, including all 27 package check-types:fast tasks.
• Standard serial check-types timed out, then its retry was interrupted after 24/27 successful packages. Full pnpm check was not rerun; prior full-suite execution encountered failures in unchanged cloud-agent process tests. These are not claimed green.
• No visual artifacts: proof handoff was blocked with proof capture timed out. No live Telegram creation or end-to-end testing has occurred.

Before enabling users, enable Bot Management Mode on the deployment's main bot, refresh its webhook subscription to include managed_bot, and run a non-production native creation/confirmation/activation smoke test including unauthorized users, attachments, background replies and disconnect. No production configuration or deployment was changed in this work.

Checklist

• The PR title follows the repo convention: [Fix], [Feat], [Improve], [Refactor], [Docs], or [Chore] followed by a user-facing description
• This PR is small and scoped to one change
• pnpm lint and pnpm check-types pass locally
• I added tests or included a clear manual validation note above
• I removed secrets, tokens, private keys, and customer data from code, logs, and screenshots
• If this change should appear in the changelog, I ran pnpm changeset

[roomote-community]

No code issues found. See task

_{Reviewed ee65eaf}