Add CI pipeline documentation and enhance syncback architecture

- Introduced a new CI pipeline documentation file outlining steps for auto-fixing formatting, running linters, building, and testing.
- Documented the Rojo syncback architecture, detailing improvements to prevent duplicate file creation and format mismatches.
- Updated syncback logic to ensure existing instances are updated instead of creating duplicates, enhancing project file management.
- Added tests for encoding instances and handling nested children to improve reliability in syncback operations.

.cursor/commands/ci.md

@@ -0,0 +1,74 @@
+# /ci - Complete CI Pipeline
+
+Run the complete CI pipeline: auto-fix all formatting, run all linters, build everything, and run ALL tests.
+
+## Instructions
+
+Execute ALL of the following steps in order. Fix issues automatically where possible.
+
+### 1. Auto-fix Lua Formatting (Stylua)
+```powershell
+stylua plugin/src
+```
+
+### 2. Auto-fix Rust Formatting
+```powershell
+cargo fmt
+```
+
+### 3. Lua Static Analysis (Selene)
+```powershell
+selene plugin/src
+```
+If there are errors, report them and offer to help fix.
+
+### 4. Rust Linting (Clippy) - Auto-fix where possible
+```powershell
+cargo clippy --fix --allow-dirty --allow-staged
+```
+Then verify with:
+```powershell
+cargo clippy --all-targets --all-features
+```
+If there are remaining warnings/errors, report them and offer to help fix.
+
+### 5. Build Everything
+```powershell
+cargo build --locked --all-targets --all-features
+```
+
+### 6. Run ALL Rust Tests
+```powershell
+cargo test --locked --all-targets --all-features
+```
+
+### 7. Run Roblox Plugin Tests (requires Roblox Studio)
+```powershell
+.\scripts\unit-test-plugin.ps1
+```
+
+## Reporting
+
+After ALL steps complete, provide a summary:
+
+```
+=== CI COMPLETE ===
+
+Formatting:
+  - Stylua: [fixed X files / no changes needed]
+  - Rustfmt: [fixed X files / no changes needed]
+
+Linting:
+  - Selene: PASS / FAIL (X issues)
+  - Clippy: PASS / FAIL (X warnings)
+
+Build: PASS / FAIL
+
+Tests:
+  - Rust: X passed, Y failed
+  - Plugin: X passed, Y failed, Z skipped
+
+Overall: PASS / FAIL
+```
+
+If any step fails, continue running the remaining steps to get a complete picture, then report all failures at the end.