ci: publish tdlib images under klhq

docs: bump TDLib version badge to 1.8.65

docs: add Alpine consumer example to Pattern A

Alpine TDLib is built with clang/libc++, so consumers need
apk add libssl3 zlib libc++ libgcc llvm-libunwind at runtime.

fix(docker): restore libtdjson.so unversioned symlink

cmake installs the linker-name as a symlink (libtdjson.so -> libtdjson.so.X.Y.Z),
but Docker COPY with a glob de-references symlinks into duplicate regular files.
The result: 33 MB wasted, and on glibc `dlopen("libtdjson.so")` fails because
ldconfig only indexes the versioned SONAME — not the unversioned regular file
sitting at /usr/local/lib/libtdjson.so.

Recreate the symlink in the runtime stage of both Dockerfiles so that
`ctypes.CDLL('libtdjson.so')` (used by TDLib's own Python example and most
ctypes-based bindings) resolves via the ldconfig cache. Pre-existing issue on
the Alpine variant too; both fixed in the same patch.

feat(docker): add Debian variant, make it the default

Default tag now ships glibc TDLib so Python/Node/Go/Java consumers
on python:slim/node:slim/bookworm/Ubuntu can load libtdjson.so
directly. Previously :latest was Alpine/musl, which silently broke
the ~85% of consumers running on glibc.

- Dockerfile: new Debian-based default (bookworm-slim, gcc + libstdc++)
- Dockerfile.alpine: prior Alpine recipe, preserved for opt-in users
- CI: 2x2 matrix builds {debian,alpine} x {amd64,arm64} with
  per-variant GHCR cache scopes to prevent libc cross-contamination
- README: rewrite with tag selection, three consumption patterns
  (COPY --from, FROM base, docker cp), compatibility matrix

Tag scheme:
  :latest, :<ver>, :<ver>-debian, :debian  -> Debian (multi-arch)
  :alpine, :<ver>-alpine                    -> Alpine (multi-arch)

BREAKING: users pinning to :latest expecting Alpine must switch to
:alpine (or :<ver>-alpine). Called out in README.

Merge branch 'master' into build

Merge branch 'master' into build

Merge branch 'master' into build

build: strip to downsize

Merge branch 'master' into build