fix(browser): allow inbound media uploads

Allow the browser upload tool to resolve OpenClaw-managed inbound media refs such as `media://inbound/<id>` and sandbox-relative `media/inbound/<id>` while preserving the existing upload-root path contract.

Keep upload-root files ahead of sandbox-relative inbound fallback, reject nested absolute inbound media files, and validate raw `media://` paths before URL normalization so traversal-shaped refs cannot resolve to direct media ids.

Verification:
- `OPENCLAW_VITEST_MAX_WORKERS=1 node scripts/run-vitest.mjs extensions/browser/src/browser/paths.test.ts --reporter=verbose`
- `OPENCLAW_VITEST_MAX_WORKERS=1 node scripts/run-vitest.mjs extensions/browser/src/browser/paths.test.ts --reporter=dot`
- `OPENCLAW_HEAVY_CHECK_LOCK_SCOPE=worktree node scripts/run-tsgo.mjs -p test/tsconfig/tsconfig.extensions.test.json --incremental --tsBuildInfoFile .artifacts/tsgo-cache/extensions-test.tsbuildinfo`
- `pnpm lint --threads=8`
- `.agents/skills/autoreview/scripts/autoreview --mode branch --base origin/main`
- `git diff --check`
- GitHub PR checks on be08e6c8a8: dependency-guard, check-lint, check-test-types, check-additional-extension-bundled, checks-fast-contracts-plugins-a, checks-fast-contracts-plugins-b all passed.

Fixes #83544.

Co-authored-by: Zee Zheng <zheng.zuo0@gmail.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

docs/cli/browser.md

@@ -205,6 +205,7 @@ File + dialog helpers:
 
 ```bash
 openclaw browser upload /tmp/openclaw/uploads/file.pdf --ref <ref>
+openclaw browser upload media://inbound/file.pdf --ref <ref>
 openclaw browser waitfordownload
 openclaw browser download <ref> report.pdf
 openclaw browser dialog --accept
@@ -215,6 +216,10 @@ Managed Chrome profiles save ordinary click-triggered downloads into the OpenCla
 downloads directory (`/tmp/openclaw/downloads` by default, or the configured temp
 root). Use `waitfordownload` or `download` when the agent needs to wait for a
 specific file and return its path; those explicit waiters own the next download.
+Uploads accept files from the OpenClaw temp uploads root and OpenClaw-managed
+inbound media, including `media://inbound/<id>` and sandbox-relative
+`media/inbound/<id>` references. Nested media refs, traversal, and arbitrary
+local paths remain rejected.
 When an action opens a modal dialog, the action response returns
 `blockedByDialog` with `browserState.dialogs.pending`; pass `--dialog-id` to
 answer it directly. Dialogs handled outside OpenClaw appear under