add the base crate and repoint the moved modules at it (#16107)

* add the base crate and repoint the moved modules at it

`libs/base` (crate `base`) takes the parts of hbb_common that only this app
uses: `fs`, `platform`, `keyboard`, `message.proto`, and 145 of the 177
`config::keys` constants. hbb_common keeps what the server names, and the 32
keys it reads itself are re-exported from `base::config::keys` so call sites
still see the full set through one path.

Sources move verbatim. The only edits inside them are `crate::` prefixes that
now have to say `hbb_common::`; `keyboard.rs` and `platform/windows.rs` are
byte-identical. The crate stays on edition 2018, the edition the moved code was
written under. `log`, `lazy_static` and `anyhow` become direct dependencies so
the bare paths in that code resolve exactly as before, and its winapi features
are spelled out rather than left to feature unification.

Two call sites outside Rust and Cargo had to follow the move: the Android
protobuf source dir, which still pointed at hbb_common/protos for message.proto,
and the three AGENTS.md entries that named hbb_common for options, protos and
file transfer.

`scrap`'s `drm` feature now forwards to `base/wayland_probe`. Left pointing at
hbb_common it would still have compiled, silently dropping the Wayland
socket-probe fallback, so that forward is verified by a build with and without
the feature.

`config::keys` carries a test asserting its names stay disjoint from the ones
hbb_common kept: the glob re-export and the local constants share a namespace,
and Rust prefers the local item silently, so a name added to both sides would
otherwise let client and server disagree with no diagnostic.

Verified: macOS and Linux, debug and release, `--all-targets`; the 177 key
constants diffed name-for-name and value-for-value; the generated protobuf types
compared before and after; every `#[cfg]` gate on a moved import checked against
its original; and every file that was `rustfmt`-clean before this change still
is, compared against master file by file. Windows is checked by inspection only
-- it cannot be compiled here.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab

* one `use` per crate, and write the rule down

`fs.rs` came out of the move with two ungated `use hbb_common::` statements,
because the original single `use crate::{...}` had to give up `message_proto`
to the new crate and the rest was left in a second block. Fold it back into one.

A scan of the whole tree for the same shape finds nothing else: every other file
with more than one top-level `use base::` or `use hbb_common::` is split by a
`#[cfg]` that does not cover the whole block, or by `pub use` next to `use`.
Those are the cases that cannot merge, so AGENTS.md now states both the rule and
the exemption.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab

---------

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

AGENTS.md

@@ -8,18 +8,24 @@
 * `src/platform/` platform-specific code
 * `src/ui/` legacy Sciter UI (deprecated)
 * `flutter/` current UI
-* `libs/hbb_common/` config / proto / shared utils
+* `libs/hbb_common/` shared with the server: rendezvous proto, sockets, `Config` core
+* `libs/base/` (crate `base`) client-only: option keys, message proto, file transfer, platform code
 * `libs/scrap/` screen capture
 * `libs/enigo/` input control
 * `libs/clipboard/` clipboard
-* `libs/hbb_common/src/config.rs` all options
+* `libs/base/src/config/keys.rs` the single import path for all options
 
 ### Key Components
 - **Remote Desktop Protocol**: Custom protocol implemented in `src/rendezvous_mediator.rs` for communicating with rustdesk-server
 - **Screen Capture**: Platform-specific screen capture in `libs/scrap/`
 - **Input Handling**: Cross-platform input simulation in `libs/enigo/`
 - **Audio/Video Services**: Real-time audio/video streaming in `src/server/`
-- **File Transfer**: Secure file transfer implementation in `libs/hbb_common/`
+- **File Transfer**: Secure file transfer implementation in `libs/base/src/fs.rs`
+
+`hbb_common` is a git submodule shared with the server, so changing it costs a
+round-trip. Put client-only code in `libs/base` instead; it is a normal
+workspace member. `base::config::keys` re-exports the handful of keys
+`hbb_common` still reads, so callers get the whole set from that one path.
 
 ### UI Architecture
 - **Legacy UI**: Sciter-based (deprecated) - files in `src/ui/`
@@ -61,6 +67,34 @@
 * Do not make formatting-only changes.
 * Keep naming/style consistent with nearby code.
 
+### Imports
+
+* One `use` per crate. Everything a file takes from the same crate goes in a
+  single braced block, not one statement per item:
+
+  ```rust
+  // no
+  use base::fs;
+  use base::message_proto::*;
+
+  // yes
+  use base::{fs, message_proto::*};
+  ```
+
+* The only reason to split is a `#[cfg(...)]` that does not apply to the whole
+  block -- an attribute binds to one item, so a differently-gated import has to
+  stand on its own. A `pub use` re-export likewise cannot join a plain `use`.
+
+  ```rust
+  #[cfg(not(feature = "flutter"))]
+  use base::fs;
+  use base::message_proto::*;
+  ```
+
+* When splitting an existing `use` because some of its items moved to another
+  crate, fold each side into that crate's existing block rather than leaving a
+  second statement behind.
+
 ### Comments
 
 * Avoid comments unless they explain a non-obvious reason, constraint, or workaround.