build: make UPX packing opt-in via COMPRESS env var (#2429)
## Summary
UPX is now disabled by default for the static build. To pack the binary
with UPX (Linux only), set `COMPRESS=1` at build time. The previous
`NO_COMPRESS` flag is removed; CI invocations and the
`static-builder-{musl,gnu}` Dockerfiles were updated accordingly. Docs
(all locales) were refreshed.
## Why drop UPX from the default?
- **AV false positives.** UPX-packed binaries get flagged routinely on
Windows and macOS, generating recurring support friction for end users.
- **Permanent memory cost.** UPX decompresses the whole binary into
anonymous memory at launch, so the OS can no longer share read-only text
pages across processes or demand-page from disk. For a long-running
server with workers, the savings on disk are paid back continuously in
RAM.
- **Startup latency.** ~100–300 ms added per launch — noticeable for
container cold starts and test runs.
- **Tooling friction.** Complicates debugging, core dumps,
SBOM/attestation, and trips up some security scanners.
- **Modest upside.** ~60% size reduction is nice, but FrankenPHP is
mostly distributed via Docker layers (cached) or downloaded once per
host. If artifact size is the concern, `xz`-compressing the release
asset gives similar savings without any of the runtime downsides.
Users who still want a packed binary can opt in explicitly with
`COMPRESS=1`.
