#11979: fix: Change rootDir to project root to allow UI compilation

The rootDir: "src" setting conflicts with include: ["src/**/*", "ui/**/*"], preventing TypeScript from compiling files in the ui/ directory. Changed to "." to encompass both directories while maintaining output structure. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR updates the root TypeScript configuration (`tsconfig.json`) to set `compilerOptions.rootDir` to the repository root (`"."`) instead of `"src"`. With the current `include: ["src/**/*", "ui/**/*"]`, this avoids TypeScript treating `ui/` files as being outside `rootDir`, which can block compilation/typechecking for the UI directory. No additional code or build logic is modified; this is a configuration-only change affecting how TS computes the common source root for included files. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - Single-line tsconfig change that aligns `rootDir` with the existing `include` patterns and is unlikely to affect outputs since the base config has `noEmit: true`. Related extending configs either inherit safely or override `rootDir` explicitly. - No files require special attention <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->