fix(projects): deterministic project identity + safe per-project persistence

Derive project.id from project.path (path_<base64url(path)>), shared helper on
both server (lib/projects/project-id.js) and client (lib/projectId.ts). Replace
random UUIDs so icons, notes, todos, actions, setup-worktree, plans and
scheduledTasks share one id across restarts and reinstalls.

Fix read-then-overwrite clobber in project-config.js: scheduled-task writes now
merge with the existing project json instead of replacing it, preserving
client-written fields that live in the same file.

On settings load migrate legacy UUID ids to canonical path ids, moving config
json, storage dir contents and icon files, and remap activeProjectId. Scan for
orphan non-path_* project configs and merge them into the canonical project
when a \$ROOT_PROJECT_PATH/<file> reference resolves on disk, logging any that
can't be matched.

Client openchamberConfig.writeOpenChamberConfig re-asserts server-owned keys
(version, scheduledTasks) on write to defeat the symmetric race. Stores and
persistence derive ids from path consistently.

packages/web/server/lib/projects/project-config.js

@@ -360,50 +360,57 @@ export const createProjectConfigRuntime = (deps) => {
     return path.join(projectsDirPath, `${safeProjectID}.json`);
   };
 
-  const readProjectConfigFromDisk = async (projectID) => {
+  const readRawProjectConfigFromDisk = async (projectID) => {
     const filePath = resolveProjectConfigPath(projectID);
-
     try {
       const raw = await fsPromises.readFile(filePath, 'utf8');
       const parsed = JSON.parse(raw);
-      if (!parsed || typeof parsed !== 'object') {
-        return createEmptyProjectConfig();
-      }
-      const tasksRaw = Array.isArray(parsed.scheduledTasks) ? parsed.scheduledTasks : [];
-      const now = Date.now();
-      const scheduledTasks = [];
-      for (const task of tasksRaw) {
-        try {
-          const normalized = normalizeTaskForStorage(task, {
-            now,
-            createId: taskIDFactory,
-            existingTask: null,
-            allowCreate: true,
-          });
-          scheduledTasks.push(normalized);
-        } catch {
-        }
-      }
-
-      return {
-        version: PROJECT_CONFIG_VERSION,
-        scheduledTasks,
-      };
+      return parsed && typeof parsed === 'object' && !Array.isArray(parsed) ? parsed : {};
     } catch (error) {
       if (error && typeof error === 'object' && error.code === 'ENOENT') {
-        return createEmptyProjectConfig();
+        return {};
       }
       throw error;
     }
   };
 
+  const readProjectConfigFromDisk = async (projectID) => {
+    const parsed = await readRawProjectConfigFromDisk(projectID);
+    const tasksRaw = Array.isArray(parsed.scheduledTasks) ? parsed.scheduledTasks : [];
+    const now = Date.now();
+    const scheduledTasks = [];
+    for (const task of tasksRaw) {
+      try {
+        const normalized = normalizeTaskForStorage(task, {
+          now,
+          createId: taskIDFactory,
+          existingTask: null,
+          allowCreate: true,
+        });
+        scheduledTasks.push(normalized);
+      } catch {
+      }
+    }
+    return {
+      version: PROJECT_CONFIG_VERSION,
+      scheduledTasks,
+    };
+  };
+
   const writeProjectConfigToDisk = async (projectID, config) => {
     const filePath = resolveProjectConfigPath(projectID);
     const parentDirectory = path.dirname(filePath);
     const temporaryPath = `${filePath}.tmp-${process.pid}-${Date.now()}-${Math.random().toString(16).slice(2)}`;
 
+    const existing = await readRawProjectConfigFromDisk(projectID);
+    const merged = {
+      ...existing,
+      version: PROJECT_CONFIG_VERSION,
+      scheduledTasks: Array.isArray(config?.scheduledTasks) ? config.scheduledTasks : [],
+    };
+
     await fsPromises.mkdir(parentDirectory, { recursive: true });
-    await fsPromises.writeFile(temporaryPath, JSON.stringify(config, null, 2), 'utf8');
+    await fsPromises.writeFile(temporaryPath, JSON.stringify(merged, null, 2), 'utf8');
     await fsPromises.rename(temporaryPath, filePath);
   };