feat(install): warn pip/Homebrew installs are unsupported (CLI, TUI, desktop) (#57225)

* feat(install): warn pip/Homebrew installs are unsupported (CLI, TUI, desktop)

pip and Homebrew are now Unsupported install methods per
website/docs/getting-started/platform-support.md. Surface a
warn-don't-block deprecation notice everywhere the install method is
already shown, pointing at the platform-support docs and noting these
installs will not receive further updates. NixOS (Tier 2) is untouched.

- hermes_cli/config.py: shared is_unsupported_install_method() /
  format_unsupported_install_warning() helpers so the wording and docs
  link stay consistent across every surface.
- hermes_cli/banner.py: generalize the existing pip-only banner
  warning to also cover Homebrew.
- hermes_cli/main.py: hermes update and hermes update --check print
  the warning before proceeding (still update; warn, don't block).
- tui_gateway/server.py: session.info gains install_warning.
- ui-tui: SessionPanel renders install_warning alongside the existing
  'N commits behind' notice.
- apps/desktop: SessionRuntimeInfo/GatewayEventPayload gain
  install_warning; applyRuntimeInfo + the live session.info event fire
  a snoozable warning toast via a new reportInstallMethodWarning(),
  mirroring the existing backend-contract-skew toast pattern. i18n
  strings added for en/zh/zh-hant/ja.
- Tests: updated pip banner assertions for the new wording, added a
  Homebrew banner test, and two tui_gateway session_info tests
  (install_warning present for pip, absent for git).

* fix(nix): make `hermes` in developement environment actually work

install modules as editable overlay with uv

* feat: print install method when running --version

* fix: correct detect install method when running from a subtree

nix/devShell.nix

@@ -28,13 +28,20 @@
         packages =
           with pkgs;
           [
+            (pkgs.runCommand "hermes" { } ''
+              mkdir -p $out/bin
+              install -Dm755 ${../hermes} $out/bin/hermes
+            '')
             uv
           ]
           ++ self'.packages.default.passthru.devDeps;
         shellHook = ''
-          echo "Hermes Agent dev shell"
           ${combinedNonNpm}
           ${hermesNpmLib.mkNpmDevShellHook npmPackageJsonPaths}
+
+          # for the devshell to pick up the src
+          export HERMES_PYTHON_SRC_ROOT=$(git rev-parse --show-toplevel)
+          echo "Hermes Agent dev shell in $HERMES_PYTHON_SRC_ROOT"
           echo "Ready. Run 'hermes' to start."
         '';
       };