[feature] Panel per-cell project picker + pnpm format infra

MegaTask root-subtasks can fan out across cells (be+fe, fe+uxui). Since a
RoboCo project is per-cell (ProjectTable.assigned_cell), a monorepo is N
per-cell projects sharing one git_url — so multi-cell IS multi-project. The
batch-review card now shows one project Select per the_work entry, scoped to
that cell's repos, instead of one Select bound to a single top-level
project_id. confirmBatch validates each cell's project is in scope and the
batch still spans >=2 distinct projects.

- prompter.ts: CellWork gains optional project_id (the per-cell picker seam).
- batch-review-card.tsx: per-cell Selects (one per the_work entry), scoped to
  the cell's projects; legacy single-cell drafts keep the one-Select path.
- use-prompter.ts: updateBatchDraftProject edits per-cell (entryIndex);  confirmBatch validates every cell; batchFromEvent parses per-cell map.

Also adds the missing pnpm format infrastructure (the panel had no formatter
at all): prettier devDep + .prettierrc.json (default-style config: 80-col,
double-quote, semi, trailing-comma-all) + .prettierignore, plus format /
format:check scripts. Only the 3 changed files above were reformatted; the
~222 pre-existing non-compliant files are left untouched (a wholesale reformat
is a separate explicit decision, not bundled into this feature).

panel/pnpm-lock.yaml

@@ -109,7 +109,7 @@ importers:
         version: 10.1.0(@types/react@19.2.8)(react@19.2.3)
       recharts:
         specifier: ^3.8.1
-        version: 3.8.1(@types/react@19.2.8)(react-dom@19.2.3(react@19.2.3))(react-is@16.13.1)(react@19.2.3)(redux@5.0.1)
+        version: 3.8.1(@types/react@19.2.8)(react-dom@19.2.3(react@19.2.3))(react-is@17.0.2)(react@19.2.3)(redux@5.0.1)
       remark-gfm:
         specifier: ^4.0.1
         version: 4.0.1
@@ -162,6 +162,9 @@ importers:
       jsdom:
         specifier: ^29.1.1
         version: 29.1.1
+      prettier:
+        specifier: ^3.8.5
+        version: 3.8.5
       tailwindcss:
         specifier: ^4
         version: 4.1.18
@@ -3230,6 +3233,11 @@ packages:
     resolution: {integrity: sha512-vkcDPrRZo1QZLbn5RLGPpg/WmIQ65qoWWhcGKf/b5eplkkarX0m9z8ppCat4mlOqUsWpyNuYgO3VRyrYHSzX5g==}
     engines: {node: '>= 0.8.0'}
 
+  prettier@3.8.5:
+    resolution: {integrity: sha512-zxcTTCedNGJM4R8sj/Cq/F0W/c4iE0afWBcBwMTRtw4WHYP9TWkYjdiH3npPRUYsXQCPR0hTU9yjovOu+E6EQA==}
+    engines: {node: '>=14'}
+    hasBin: true
+
   pretty-format@27.5.1:
     resolution: {integrity: sha512-Qb1gy5OrP5+zDf2Bvnzdl3jsTf1qXVMazbvCoKhtKqVs4/YK4ozX4gKQJJVyNe+cajNPn0KoC0MC3FUmaHWEmQ==}
     engines: {node: ^10.13.0 || ^12.13.0 || ^14.15.0 || >=15.0.0}
@@ -7228,6 +7236,8 @@ snapshots:
 
   prelude-ls@1.2.1: {}
 
+  prettier@3.8.5: {}
+
   pretty-format@27.5.1:
     dependencies:
       ansi-regex: 5.0.1
@@ -7317,7 +7327,7 @@ snapshots:
 
   react@19.2.3: {}
 
-  recharts@3.8.1(@types/react@19.2.8)(react-dom@19.2.3(react@19.2.3))(react-is@16.13.1)(react@19.2.3)(redux@5.0.1):
+  recharts@3.8.1(@types/react@19.2.8)(react-dom@19.2.3(react@19.2.3))(react-is@17.0.2)(react@19.2.3)(redux@5.0.1):
     dependencies:
       '@reduxjs/toolkit': 2.12.0(react-redux@9.3.0(@types/react@19.2.8)(react@19.2.3)(redux@5.0.1))(react@19.2.3)
       clsx: 2.1.1
@@ -7327,7 +7337,7 @@ snapshots:
       immer: 10.2.0
       react: 19.2.3
       react-dom: 19.2.3(react@19.2.3)
-      react-is: 16.13.1
+      react-is: 17.0.2
       react-redux: 9.3.0(@types/react@19.2.8)(react@19.2.3)(redux@5.0.1)
       reselect: 5.1.1
       tiny-invariant: 1.3.3