docs: Overhaul AI documentation (#29747)

To support the Agentic Editing launch. To dos before merging:

- [ ] Anything marked as `todo!` within `docs/src` (Anyone)
- [x] Check all internal links (Joe)
- Joe: I checked all links and fixed all aside from a few that I
annotated with `todo!` comments
- [ ] Update images (Danilo)
- [ ] Go over / show images of tool cards in agent panel overview
(Danilo)
- [ ] Point billing FAQ to new billing docs (Joe)
- [x] Redirects external links
    - [ ] Needs testing
- [x] Delete old docs
- [ ] Ensure all mentioned bindings use the `{#kb ...}` format and that
they are rendering correctly
- [ ] All agent-related actions are now `agent::` and not `assistant::`
- [x] Mention support of `.rules` files in `rules.md`

Release Notes:

- N/A

---------

Co-authored-by: Joseph T. Lyons <josephtlyons@gmail.com>
Co-authored-by: morgankrey <morgankrey@gmail.com>
Co-authored-by: Smit Barmase <37347831+smitbarmase@users.noreply.github.com>
Co-authored-by: Ben Kunkle <Ben.kunkle@gmail.com>
Co-authored-by: Peter Tripp <peter@zed.dev>
Co-authored-by: Ben Kunkle <ben@zed.dev>
Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>
Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>

docs/src/ai/privacy-and-security.md

@@ -0,0 +1,27 @@
+# Privacy and Security
+
+## Philosophy
+
+Zed aims to collect on the minimum data necessary to serve and improve our product.
+
+We believe in opt-in data sharing as the default in building AI products, rather than opt-out, like most of our competitors. Privacy Mode is not a setting to be toggled, it's a default stance.
+
+As an open-source product, we believe in maximal transparency, and invite you to examine our codebase. If you find issues, we encourage you to share them with us.
+
+It is entirely possible to use Zed without sharing any data with us and without authenticating into the product. We're happy to always support this desired use pattern.
+
+## Documentation
+
+- [Telemetry](../telemetry.md): How Zed collects general telemetry data.
+
+- [AI Improvement](./ai-improvement.md): Zed's opt-in-only approach to data collection for AI improvement, whether our Agentic offering or Edit Predictions.
+
+- [Accounts](../accounts.md): When and why you'd need to authenticate into Zed, how to do so, and what scope we need from you.
+
+## Legal Links
+
+- [Terms of Service](https://zed.dev/terms-of-service)
+- [Terms of Use](https://zed.dev/terms)
+- [Privacy Policy](https://zed.dev/privacy-policy)
+- [Zed's Contributor License and Feedback Agreement](https://zed.dev/cla)
+- [Subprocessors](https://zed.dev/subprocessors)