Add docs for new standalone query cmake project generator

Author: jungmair

docs/ForDevelopers/Debugging.md

@@ -19,6 +19,9 @@ For the following instructions, we assume that LingoDB was built in Release mode
   * If yes: debug with this backend. 
   * If not: you should use the [LLVM Debug Backend](#llvm-debug-backend)
 
+## Guide: Quick iteration through standalone CMake projects
+As discussed [here](StandaloneQuery.md), LingoDB can compile SQL queries to C++ queries and create standalone CMake projects that allow for quick iterations, without adapting the compilation pipeline at all.
+
 ## Components for Debugging and Profiling
 ### Location Tracking in MLIR
 In MLIR, every operation is associated with a *Location*, that must be provided during operation creation.

docs/ForDevelopers/StandaloneQuery.md

@@ -0,0 +1,67 @@
+---
+title: Generating a standalone CMake project for a specific query
+---
+Sometimes, you want to quickly experiment with speeding up a particular SQL query without diving into LingoDB’s full compiler pipeline. For this, LingoDB provides a script that generates a standalone, minimal CMake project for just that query. The query is compiled ahead-of-time into C++ and linked against LingoDB’s runtime.
+
+
+### 1. Generate CMake project for your query
+
+**Command:**
+```bash
+bash tools/standalone-query/create.sh \
+  my_query.sql \
+  my/db/dir \
+  build-dir \
+  /absolute/path/to/experiments/my-query \
+  speedup-query
+```
+
+- **my_query.sql**: path to your `.sql` file.
+- **my/db/dir**: path to an existing LingoDB database directory.
+- **build-dir**: directory containing the `compile-to-cpp` executable, e.g., `build/lingodb-debug`
+- **/absolute/path/to/experiments/my-query**: new worktree directory (must *not* exist).
+- **speedup-query**: name for the experimental branch (must *not* exist).
+
+This script performs the following steps:
+1. generate sparse git worktree (to make sure that you can work with git/commit your changes)
+2. prepares the project (e.g., prepares custom CMakeLists.txt)
+3. compiles the SQL query to a C++ file that is placed in the new CMake project
+4. Finally, it prints some helpful information, for example:
+```bash
+
+== Standalone query worktree created ==
+Branch: speedup-query
+Worktree directory: /home/alice/projects/experiments/my-query
+
+== Commands to build the standalone query executable ==
+cd /home/alice/projects/experiments/my-query
+mkdir build && cd build
+cmake -DCMAKE_BUILD_TYPE=Release ..
+cmake --build . -j$(nproc)
+
+== Commands to run the standalone query executable ==
+./main /home/alice/projects/lingodb/db-dir
+
+== Commands to clean up the worktree ==
+cd /home/alice/projects/lingodb
+git worktree remove /home/alice/projects/experiments/my-query --force
+(optional) git branch -D speedup-query
+```
+
+---
+
+### 2. Use the generated project
+
+- It’s a **normal CMake/C++** project—use your debugger, profiler, or editor of choice.
+- Feel free to edit **any** sources:
+    - Tweak the generated `query.cpp`.
+    - Modify runtime code.
+- Because it lives in a separate Git worktree & branch, your experiments won’t affect the main codebase.
+
+---
+
+### 3. Commit selected changes
+
+- Any fixes or optimizations you make to runtime components will live on your **experimental branch**.
+- When ready, switch back to your main worktree and either cherry-pick or merge your changes
+