refactor: normalize .ts import suffixes to .js across 9 files

21 relative imports in src/fingerprint/{loader,merge,resolver,schema}.ts, src/{betas,env,models,thinking}.ts, and src/request/profile-resolver.ts used .ts suffix while the rest of the codebase (~200 imports) uses .js. Mechanical sed rewrite; no build or runtime change because tsc resolves both to the same compiled output. Resolves desloppify cluster import-suffix-normalize. 181/181 fingerprint+request tests pass.