#7458: fix: pass filename through to WhatsApp document sends (#7446)

## Summary Fixes #7446 - When sending documents via WhatsApp, recipients see "file" instead of the actual filename. ## Root Cause The `filename` parameter wasn't being passed through the WhatsApp send chain. The `send-api.ts` file had a hardcoded `fileName: "file"` for document payloads. ## Changes 1. **`src/channels/plugins/types.adapters.ts`**: Added `filename?: string` to `ChannelOutboundContext` type 2. **`src/web/active-listener.ts`**: Added `fileName?: string` to `ActiveWebSendOptions` type 3. **`src/web/outbound.ts`**: - Added `fileName` option to `sendMessageWhatsApp` - Capture `fileName` from `loadWebMedia` result - Use provided fileName or fall back to the one from loaded media 4. **`src/web/inbound/send-api.ts`**: Use `sendOptions?.fileName || "file"` instead of hardcoded "file" 5. **`src/channels/plugins/outbound/whatsapp.ts`**: Pass `filename` to `sendMessageWhatsApp` 6. **`extensions/whatsapp/src/channel.ts`**: Pass `filename` to `sendMessageWhatsApp` ## Testing - `pnpm tsgo` - No type errors - `pnpm lint` - No warnings or errors The fix ensures that: 1. If a filename is explicitly provided via the message tool, it's used 2. Otherwise, the filename is extracted from the loaded media (via `loadWebMedia`) 3. Falls back to "file" only if neither is available <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR threads a document filename through the WhatsApp outbound pipeline so recipients see the actual document name instead of a hardcoded `"file"`. It extends the outbound context/types to carry `filename`, maps that to `fileName` in web send options, plumbs it through `sendMessageWhatsApp` (including falling back to `loadWebMedia`’s derived filename), and uses it in the Baileys document payload. One gap: the existing outbound unit test for document sends (`src/web/outbound.test.ts`) doesn’t assert the new filename propagation, so a regression in this feature wouldn’t be caught by tests. <h3>Confidence Score: 4/5</h3> - This PR is safe to merge with low functional risk. - Changes are small and localized, mainly plumbing a new optional `fileName` through existing WhatsApp send paths. The only notable issue is test coverage not being updated to assert the new behavior, which increases regression risk without affecting runtime correctness directly. - src/web/outbound.test.ts <!-- greptile_other_comments_section --> **Context used:** - Context from `dashboard` - CLAUDE.md ([source](https://app.greptile.com/review/custom-context?memory=fd949e91-5c3a-4ab5-90a1-cbe184fd6ce8)) - Context from `dashboard` - AGENTS.md ([source](https://app.greptile.com/review/custom-context?memory=0d0c8278-ef8e-4d6c-ab21-f5527e322f13)) <!-- /greptile_comment -->