refactor(desktop): align install layout with install.ps1 / install.sh

Make the desktop app's runtime layout match what scripts/install.ps1 and
scripts/install.sh produce, so a desktop-only user and a CLI-only user end
up with the same files in the same places and can share one install.

Layout
- ACTIVE_HERMES_ROOT = HERMES_HOME/hermes-agent  (was: process.resourcesPath/hermes-agent, read-only)
- VENV_ROOT          = HERMES_HOME/hermes-agent/venv  (was: userData/hermes-runtime)
- desktop.log        = HERMES_HOME/logs/desktop.log  (was: userData/desktop.log)
- HERMES_HOME default: %LOCALAPPDATA%\hermes on Windows, ~/.hermes elsewhere

The packaged .app/.exe still ships a read-only payload at
process.resourcesPath/hermes-agent (FACTORY_HERMES_ROOT). On first launch
or after an installer-driven upgrade we sync factory -> active, then
provision the venv and run pip install -e . against the active root.

Key behaviors
- Pin HERMES_HOME in the spawned Python's env so get_hermes_home() resolves
  to the same path resolveHermesHome() picked. Without this, Python falls
  back to ~/.hermes on every platform - fine on mac/linux, a split-state
  bug on Windows where our default is %LOCALAPPDATA%\hermes.
- Detect developer installs by .git presence at ACTIVE; never overwrite
  a user's checkout via factory sync.
- Marker at ACTIVE/.hermes-desktop-runtime.json (schema v4) tracks
  pyproject hash + factory version + runtime schema version. depsFresh
  fast-paths when nothing changed.
- Dev (npm run dev) prefers SOURCE_REPO_ROOT over ACTIVE so devs run
  their local edits, not whatever's under HERMES_HOME.
- Better error messages distinguish "no payload" from "no Python".
- Preserve a legacy ~/.hermes on Windows when no %LOCALAPPDATA%\hermes
  exists, so users with prior pip/manual installs aren't orphaned.

pyproject.toml
- Promote fastapi, uvicorn[standard], ptyprocess (non-Windows), and
  pywinpty (Windows) to main dependencies. The dashboard backend
  (hermes dashboard) needs them at runtime; the previous lazy-import
  fallback was a footgun for fresh installs.
- Empty the [pty] optional-extra; kept as a no-op back-compat alias for
  any existing pip install hermes-agent[pty] invocations.

Drops the hardcoded BUNDLED_RUNTIME_REQUIREMENTS list in main.cjs - the
desktop now installs whatever pyproject.toml says, single source of truth.

Files
- apps/desktop/electron/main.cjs:    runtime layout, HERMES_HOME pin,
                                      factory->active sync, marker v4
- apps/desktop/scripts/test-desktop.mjs:  track new venv location
- apps/desktop/README.md:            new Setup, Runtime Bootstrap, and
                                      Debugging sections
- pyproject.toml:                    fastapi/uvicorn/pty backends in main
                                      dependencies; [pty] extra emptied

Tested locally on Windows: npm run dev boots cleanly, sessions land at
the new location, type-check + lint + test:desktop:platforms all pass.
Verified end-to-end on a fresh Win11 VM via dist:win installer.

Known gaps (filed as follow-ups, not in this PR):
- Skills not seeded on packaged installs (sync_skills only runs in
  cmd_chat, not cmd_dashboard). Need to move to shared pre-dispatch.
- Git Bash not bundled or detected; agent's terminal tool errors out
  with a useful message but desktop bootstrapper should pre-flight it.
- install.ps1 / install.sh should be decomposed into composable phase
  libraries so the desktop bootstrapper can reuse them as a single
  source of truth across all install surfaces.

pyproject.toml

@@ -49,6 +49,10 @@ dependencies = [
   # (which is a silent killer on Windows — see CONTRIBUTING.md) and
   # `os.killpg` (which doesn't exist on Windows).
   "psutil>=5.9.0,<8",
+  "fastapi>=0.104.0,<1",
+  "uvicorn[standard]>=0.24.0,<1",
+  "ptyprocess>=0.7.0,<1; sys_platform != 'win32'",
+  "pywinpty>=2.0.0,<3; sys_platform == 'win32'",
 ]
 
 [project.optional-dependencies]
@@ -70,8 +74,10 @@ voice = [
   "numpy>=1.24.0,<3",
 ]
 pty = [
-  "ptyprocess>=0.7.0,<1; sys_platform != 'win32'",
-  "pywinpty>=2.0.0,<3; sys_platform == 'win32'",
+  # Kept as a no-op back-compat alias — `ptyprocess` and `pywinpty` are now
+  # in the main `dependencies` list (with the same platform markers), so
+  # any existing `pip install hermes-agent[pty]` invocations resolve cleanly
+  # without pulling in extra packages.
 ]
 honcho = ["honcho-ai>=2.0.1,<3"]
 mcp = ["mcp>=1.2.0,<2"]