feat(scripts): bump npm deps to absolute latest with peer-dep conflict resolution

Rewrites update.py with npm_bump_and_resolve():
- Restores package.json from git for a clean baseline each run
- Uses npm-check-updates to bump all deps to absolute latest
- Iteratively resolves peer dep conflicts by patching package.json directly:
  - Tight peer constraints (no ||): apply the range verbatim
  - "Could not resolve" direct deps: downgrade by one major (^N → ^N-1)
  - Broad || ranges skipped — they include the latest major and cause loops
- Fixes build-extension.sh invocation to run from ROOT (not scripts/)

Result: @eslint/js and eslint held at ^9 (eslint-plugin-mozilla blocks v10),
typescript held at >=4.8.4 <6.0.0 (typescript-eslint blocks v6),
all other deps bumped to latest.

Author: vringar