feat(chat): support moving live sessions between chat pane and my workstation

[Harry19081]

Summary

• Move ORGII, ORG2, and externally loaded sessions between Chat Panel and My Station through overflow/context menus, sidebar entry points, and drag and drop between both tab bars.
• Keep the same live session pipeline attached during transfer and while the Raw view is selected, preserving streaming and writable imported-session continuation.
• Share the session dropdown, compact/pagination/token/status preferences, status bar, modal actions, and monochrome-aware session icon treatment across both surfaces.
• Add the Source Control-style GUI / Raw header switch plus a source-aware raw transcript viewer with refresh and copy support.
• Route historical projection version and session identity from the same atom source as its events so previous rounds load reliably.

Test plan

• Focused Vitest suite: 6 files, 31 tests passed.
• ESLint passed for all 43 changed TypeScript and TSX files.
• Production webpack build passed in 39.1 seconds.
• Pre-commit lint-staged, scoped TypeScript, circular-dependency, and repository statistics gates passed.
• git diff --check and Prettier checks passed.
• Architecture and frontend UI audit reports updated.

Note: the exact-config repository-wide typecheck currently reports an unrelated dirty-tree String.replaceAll ES2020 library mismatch in src/api/tauri/agent/cliTerminalSession.ts. No feature file reports a TypeScript error, and the scoped pre-commit TypeScript check and production build pass.

Submit checklist

• The PR is focused and has a scoped Conventional Commits title.
• Relevant checks were run and are documented above.
• No secrets, private config, generated output, or unrelated formatting changes are included.
• Required audit docs and locale updates are included.