Assuming the conditions are met for -dev_fast to work (linux, debug, x86-64
without sanitizers), the -dev_fast now defaults to true.
download-v8 make target always downloads the .a (as before) and on linux x86-64
it also downloads the .so.
Supports prebuild-v8 shared library and adds a `download-v8-shared` make target.
Depends on: https://github.com/lightpanda-io/zig-v8-fork/pull/198
The auto-discovery of the .so is done in the build.zig, which is different than
the auto-discovery of the .a which is done in the Makefile. This is intentional
and if we inverse -Ddev_fast so that it's on by default, the .a's auto discovery
will be moved to build.zig for consistency and explicitness. As-is, we have no
way to tell whether -Dprebuilt_v8_path=v8.a is being injected by Makefile or
is explicit (which isn't a problem so long as we're not doing dev_fast by
default).
Reciprocal pointers so humans landing in CONTRIBUTING.md discover
the agent/operational conventions in AGENTS.md, and agents landing
in AGENTS.md discover the CLA gate and pre-PR checks. Adds a short
Development section (test + fmt commands) and a Before-opening-a-PR
checklist to CONTRIBUTING.md; CLA paragraph preserved verbatim and
moved to its own section.
Karl Seguin