tree downloads every cloud-synced file it lists

**Describe the bug**

The `tree` tool prints a line count beside each file, and gets that count by
reading every file in the walk.

Reading is exactly what hydrates a cloud placeholder. OneDrive Files On-Demand,
iCloud Drive and other File Provider backends leave "cloud-only" files on disk
as placeholders holding no data. Enumerating a directory and stat-ing its
entries is free and touches no network, but opening one for data blocks while
the provider downloads the whole file.

So a single `tree` call on a synced folder pulls the entire remote tree down.
The user never opened those files and the agent never edited them.

Three things make this worse than a slow tool call:

1. **The user is never asked.** `tree` is annotated `read_only_hint = true`, so
`permission_inspector.rs` files it under auto-approved and it never prompts.
The `developer` extension is `default_enabled: true`. Nothing surfaces that
the call is about to move gigabytes.
2. **It is invisible afterwards.** A read that fails returns a line count of 0,
so a large binary renders as `[0]` — the download happened, the output says
nothing about it.
3. **Metered links.** On tethering or a capped corporate connection this is a
real cost, not just latency.

Adjacent, same function: the walk has no entry ceiling and the reply has no cap,
so a synced home directory can bury the response at the default depth of 2.

Who it affects: anyone whose working directory sits inside a cloud-synced
folder. On Windows that is the default rather than the exception — with Known
Folder Move enabled, `Documents` and `Desktop` *are* OneDrive, so a user does
not have to do anything unusual to be inside one.

---

**To Reproduce**

1. On Windows, enable OneDrive Files On-Demand and ensure a folder holds
cloud-only files (Explorer shows a cloud icon rather than a green tick).
2. Point goose at that folder and have it call `tree`.
3. Watch the OneDrive tray icon — it starts syncing, and files that were
cloud-only become locally available.

Same on macOS with an iCloud Drive or OneDrive folder that has evicted files.

---

**Expected behavior**

Listing a directory should not download its contents. `tree` should decide from
metadata — which the walk already holds — whether reading a given file is safe,
rather than reading unconditionally. Both platforms expose a placeholder marker
in the file's attributes, and the directory entry already carries the size, so a
skipped file can still be described usefully.

---

**Please provide the following information**
- **OS & Arch:** Windows Server 2022 build 20348, AMD64 - the machine the measurements
in the comment below were taken on. Originally reported by a user on a corporate
Windows desktop whose exact build I did not capture. The same code path exists on
macOS with File Provider (iCloud Drive / OneDrive), but I have not measured it there.
- **Interface:** UI (the tool is reachable from CLI too)
- **Version:** observed on a downstream build tracking goose; the affected code
path is unchanged in current `main`, verified at 7a678c1c8
- **Extensions enabled:** `developer` (platform extension, on by default)
- **Provider & Model:** not provider-specific

---

**Additional context**

Source: `crates/goose/src/agents/platform_extensions/developer/tree.rs` —
`count_file_lines` calls `fs::read_to_string` on every entry that
`collect_tree` classifies as a file.

I have a patch with tests against current `main` and am happy to open the PR
once this reaches Ready.

The bug is in crates/goose/src/agents/platform_extensions/developer/tree.rs, specifically the count_file_lines function that calls fs::read_to_string. Start by examining the collect_tree logic and the file metadata available during the walk. On Windows, check for FILE_ATTRIBUTE_RECALL_ON_DATA_ACCESS; on macOS, check NSURLUbiquitousItemDownloadingStatusKey. Modify the logic to skip reading placeholder files, using size from metadata instead. Run tests to ensure tree still works on local files.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.