Use CLI flags instead of environment variables for master config

Replace env var parsing with Go's flag package:
- --watch (default: ../express)
- --workers (default: 1)
- --base-port (default: 3000)
- --port (default: 8080)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

TODO.md

@@ -1,9 +1,17 @@
 - [ ] Update check script:
-  - [ ] Run `go fmt` on all .go files
-  - [ ] Run prettier on all .ts files
+  - [x] shellcheck on shell scripts
+  - [x] `go vet` on go files
+  - [x] `golangci-lint` on go files
+  - [x] Run `go fmt` on all .go files
   - [ ] Eventually, run unit tests
 
-- [ ] Adapt master program so that it reads configuration from command line
+- [x] Reimplement fixup.sh
+  - [x] run shfmt on all shell scripts (and the files they `source`)
+  - [x] Run `go fmt` on all .go files
+  - [x] Run ~~prettier~~ biome on all .ts files and maybe others
+
+
+- [x] Adapt master program so that it reads configuration from command line
   args instead of from environment variables
   - Should have sane defaults
   - Adding new arguments should be easy and obvious
@@ -19,3 +27,9 @@
   - [ ] update framework-managed pnpm
   - [ ] update pnpm-managed deps
   - [ ] rebuild golang programs
+
+- [ ] If the number of workers is large, then there is a long lapse between
+      when you change a file and when the server responds
+  - One solution: start and stop workers serially: stop one, restart it with new
+    code; repeat
+  - Slow start them: only start a few at first