chore: remove dead code (59 unused files + ~125 unused exports) (#1835)

* chore: remove dead/unreferenced files across ui, vscode

Remove 59 unused source files (components, hooks, lib utils, stores,
barrels, and orphaned vscode github modules) that are not imported by
any entry-reachable code. Also drop a stale test mock for the removed
execCommands module.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* refactor: remove unused exported symbols (types, functions, consts, hooks)

Remove exported symbols whose identifier is referenced nowhere in the
repository (verified via repo-wide search), across ui types/contracts,
lib utilities, sync layer, stores, and components. Also drop the few
imports/private helpers orphaned by these removals.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* refactor: remove more unused exports (desktop, shortcuts, worktree, vscode)

Continue removing repo-wide unreferenced exported functions, consts and
types across lib/desktop, shortcuts, worktreeSessionCreator, sync, and
vscode gitService, with cascading orphaned helpers/imports cleaned up.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* chore: add dead-code cleanup tooling

* refactor: checkpoint dead-code cleanup

* refactor: remove dead-code suppressions

---------

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>
Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/web/server/lib/quota/DOCUMENTATION.md

@@ -7,7 +7,6 @@ This module fetches quota and usage signals for supported providers in the web s
 - `packages/web/server/lib/quota/index.js`: public entrypoint imported by `packages/web/server/index.js`.
 - `packages/web/server/lib/quota/routes.js`: Express route registration for quota endpoints.
 - `packages/web/server/lib/quota/providers/index.js`: provider registry, configured-provider list, and provider dispatcher.
-- `packages/web/server/lib/quota/providers/interface.js`: JSDoc provider contract used as implementation reference.
 - `packages/web/server/lib/quota/providers/google/`: Google-specific auth, API, and transform modules.
 - `packages/web/server/lib/quota/utils/`: shared auth, transform, and formatting helpers.
 
@@ -42,6 +41,9 @@ All providers should return results via shared helpers to preserve API shape:
 - Optional field: `error`
 - Unsupported provider requests should return `ok: false`, `configured: false`, `error: Unsupported provider`
 
+Provider modules must export `providerId`, `providerName`, `aliases`, `isConfigured(auth?)`, and `fetchQuota()`.
+`fetchQuota()` should return a quota result with `usage.windows` keyed by window name (for example `5h`, `7d`, `daily`) and optional provider-specific `usage.models` data.
+
 ## Add a new provider (quick steps)
 1. Choose module shape based on complexity:
    - Simple providers: create `packages/web/server/lib/quota/providers/<provider>.js`.