Clean up LSP diagnostics across backend and frontend

Backend (nvcurve/):
- hal/fans.py, hal/limits.py, hal/gpu.py: replace conditional pynvml
  imports with the established 'pynvml: Any = _pynvml_import' pattern
  (fixes ~50 'possibly unbound' errors); type the result dicts; guard
  query_interface() results; explicit uuid/pci-bus parsing (int, hex
  convention documented); modernize Optional[T] -> T | None
- cli.py: fix 'curve_state' possibly-unbound and snap_path None handling
  in cmd_setup; wrap unchecked int()/open()/makedirs() calls in
  try/except with clean CLI errors; add module logger for silent
  except-pass blocks; raise ... from exc; fix unused loop vars and
  set-comprehension
- hal/snapshot.py: filepath: str | None; wrap all file ops; sorted
  imports; remove unused CT_POINTS import
- daemon.py: extract 0o666 to _SOCKET_MODE constant (intentional for
  /run sockets) with nosemgrep
- server.py: nosemgrep for Python 3.7-compat false positive (project
  requires >= 3.12); log previously-swallowed exception
- profiles/native.py, profiles/apply.py: wrap file ops and int(k)
  profile-key parsing; sorted imports; modernize typing

Frontend (frontend/src):
- Add .js extensions to all relative imports (standard TS-ESM; Vite
  resolves .js -> .ts)
- React.FormEvent (deprecated in React 19 types) -> React.SubmitEvent
- catch (e: any) -> catch (e: unknown) + instanceof Error narrowing
- React-hooks: move ref writes from render into effects; convert
  viewport reset to render-phase state adjustment; split
  selectPoint(index, multi) into selectPoint + togglePoint (no flag
  argument); remove non-null assertion
- Static inline styles -> Tailwind classes (dynamic positioning/cursor
  styles kept)
- Remove non-standard 'container' option from scrollIntoView (browsers
  ignore unknown options) which had orphaned a @ts-expect-error
- Object.fromEntries for Map -> Record conversion

Tooling:
- .gitignore: ignore .codegraph/ local tool data

Verified: tsc --noEmit, vite production build, python imports, and
full LSP scan (0 errors/warnings in both projects).

frontend/src/components/CurveEditor/CurveTooltip.tsx

@@ -1,5 +1,5 @@
-import { fmt } from '../../utils/units';
-import type { VFPoint } from '../../types';
+import { fmt } from '../../utils/units.js';
+import type { VFPoint } from '../../types.js';
 
 interface Props {
   point: VFPoint;
@@ -21,15 +21,7 @@ export function CurveTooltip({ point, pendingDeltaKhz, isClamped }: Props) {
 
   return (
     <div
-      style={{
-        position: 'absolute',
-        right: 16,
-        bottom: 16,
-        pointerEvents: 'none',
-        zIndex: 50,
-        width: 172,
-      }}
-      className="bg-zinc-800 border border-zinc-700 rounded-md p-2 text-xs shadow-xl"
+      className="absolute right-4 bottom-4 pointer-events-none z-50 w-[172px] bg-zinc-800 border border-zinc-700 rounded-md p-2 text-xs shadow-xl"
     >
       <div className="text-zinc-400 mb-1">Point {point.index}</div>
       <div className="text-zinc-200">