fix(validate-schema): reject platform-invalid Actor version formats

[kuntal1461]

What changed and why

apify validate-schema accepted any version value in .actor/actor.json without checking it against the format the platform build API enforces. A user who wrote version: "1.0.0" (three-part SemVer) would get a clean local result, then hit a cryptic admission error after upload — consuming a build slot.

• Add validateActorVersion() at the start of the all-schemas scan (validateAllSchemas); it is skipped when a path argument is given, so apify validate-schema ./INPUT_SCHEMA.json is unaffected.
• Regex /^(0|[1-9]\d*)\.(0|[1-9]\d*)$/: MAJOR.MINOR, non-negative integers, no leading zeros, no upper-bound cap. Derived from the confirmed platform constraint (same regex used in the sibling push-side guard).
• TODO comment references apify-shared-js chore(deps): lock file maintenance #655 where the shared constant will eventually land; the local definition will become a swap-in.
• 100.0 and 1.100 deliberately pass — the platform accepts them; an earlier draft capped at 99, which was incorrect.

Fixes

Fixes #1364

Files changed

• src/lib/input_schema.ts — adds ACTOR_VERSION_REGEX + validateActorVersion()
• src/commands/validate-schema.ts — wires validateActorVersion into the all-schemas path
• test/local/commands/validate-schema.test.ts — regression tests for confirmed invalid (1.0.0, 01.0, 1.01) and valid (0.0, 1.0, 99.99, 100.0, 1.100) formats

Notes

• No changes to apify push — push-side fail-fast is separate work.
• No new dependencies; no install-size impact.