doc(doc-site): document the CLI tools codescan ships

[fredbi]

The site described codescan as a library and as a terminal UI, and its options as Go struct fields. The commands now share one flag surface and one configuration contract, so a field is one of three spellings of the same knob — and the command most people will put in a build had no page at all.

Getting started:

• a page for genspec: the two output streams, choosing the document, the diagnostics flags, what -validate checks and how a finding is located, and what each exit status means. It closes on genspec-wasi, for a sandbox or an image with no Go in it.
• the terminal UI page catches up with the shared surface: -loader replaces -toolchain-free-loader, every option is both a flag and a live toggle rather than one or the other, -packages is the deprecated spelling of positional patterns, and the TUI does read a configuration file. The run-cost card and the -profile flags are documented, with captures of both.

Usage, a section until now holding a placeholder that linked out to GitHub for material this site has carried since June:

• the options reference moves here from the maintainers compendium, every row gaining the flag that writes it and the section a .codescan.yaml addresses it in;
• a page for the rules those two columns follow: how a flag name derives from a field, what a configuration file may hold, where it is looked for, and that anything typed wins over it.

Maintainers gains a page on how the commands are put together: why each lives in the module it does, the guard that fails the build when an option lands with no flag, and the seam that keeps the configuration package usable from the WebAssembly build.

Also: the playground box can be expanded or taken full screen, for a reader who has stopped reading and started using it; the version parameters generated at build time are rendered rather than ignored; and the worked petstore example becomes the first tutorial instead of an orphan under the placeholder.

The flag and section columns of the reference were filled from the flag tables themselves rather than transcribed, so all forty rows are the code's answer.

Change type

Please select: 🆕 New feature or enhancement|🔧 Bug fix'|📃 Documentation update

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Checklist

• I have signed all my commits with my name and email (see DCO. This does not require a PGP-signed commit
• I have rebased and squashed my work, so only one commit remains
• I have added tests to cover my changes.
• I have properly enriched go doc comments in code.
• I have properly documented any breaking change.