fix: list and open sessions across project directories

Sessions outside the server's launch directory were invisible and returned
404 on open, leaving the model picker empty. List without the SDK's
process-cwd filter and normalize working directories at the API boundary and
when reading stored session data, tolerating separator/normalization
differences (including Windows backslash vs forward slash). Requires Pi
coding agent SDK 0.78.0 or newer.

package.json

@@ -71,7 +71,7 @@
   },
   "devDependencies": {
     "@changesets/cli": "^2.31.0",
-    "@earendil-works/pi-coding-agent": "^0.74.0",
+    "@earendil-works/pi-coding-agent": "^0.79.1",
     "@eslint/js": "^10.0.1",
     "@types/node": "^24.10.1",
     "@types/ws": "^8.18.1",
@@ -82,7 +82,7 @@
     "typescript-eslint": "^8.59.2",
     "vite": "^7.2.4",
     "vitest": "^4.1.5",
-    "@earendil-works/pi-ai": "^0.74.0"
+    "@earendil-works/pi-ai": "^0.79.1"
   },
   "publishConfig": {
     "access": "public"
@@ -100,8 +100,8 @@
   "homepage": "https://pi-web.dev/",
   "packageManager": "[email protected]",
   "peerDependencies": {
-    "@earendil-works/pi-coding-agent": ">=0.74.0 <1",
-    "@earendil-works/pi-ai": ">=0.74.0 <1"
+    "@earendil-works/pi-coding-agent": ">=0.78.0 <1",
+    "@earendil-works/pi-ai": ">=0.78.0 <1"
   },
   "keywords": [
     "pi-package",