v2.3.0 — Runner selection, colored output, and capability reporting

Runner selection, colored output, and runner capability reporting

A cluster of related improvements to how scripts get routed to runners, what
you can see about a runner's actual capabilities, and how output is
displayed.

Why

With multiple runners in a fleet, "which runner will run this?" and "why did
this fail?" were both harder to answer than they should be — assignment was
always automatic, output with color codes rendered as literal escape-sequence
garbage, and there was no visibility into a runner's own health (version,
architecture, disk space) beyond whether it was online.

What's new

• Manual runner selection — Run Script and Scheduled Jobs pages let you
  pick a specific runner instead of Auto (least-busy). The picker only lists
  runners that report the script's language as installed; RunnerAssignmentService
  enforces this server-side too, with a specific failure message
  (offline / at capacity / wrong language) instead of a generic one.
  Scheduled jobs can be permanently pinned to a runner via
  preferred_runner_id.
• Real ANSI color rendering — script output now renders actual color and
  style (16-color palette, bold, dim, italic, underline, reverse, blink)
  instead of showing raw \x1b[...m escape codes as literal text. Applies to
  both the live Run Script terminal and the static History detail view. New
  resources/js/ansi.js (24 unit tests) plus three sample scripts
  (ANSI Color Palette (Bash), ANSI Color Palette (PowerShell),
  Colored Status Report (Bash)) to try it out immediately.
• Runner capability visibility — History shows which runner ran each
  script (with live status), and Settings → Runners now has an expandable
  detail row showing per-language support, the runner's own binary version,
  CPU architecture, and free/total disk space on its temp directory — so a
  stale runner or one running low on disk is visible instead of silently
  failing later.
• UI polish — Run Script's output terminal now fills the page instead of
  stopping at a fixed height, and correctly clears when switching between
  scripts instead of leaking the previous script's output underneath the
  newly-selected one.
• Runner bugfix — fixed a PATH-resolution mismatch where the runner could
  report an interpreter (e.g. a Homebrew-installed pwsh) as available in
  its heartbeat, but actual script execution still failed to find it because
  it only checked the process's inherited PATH, not the same fallback
  search used for detection. Runner binary bumped to 1.2.0.

Upgrading

Two new migrations (preferred_runner_id on scheduled_jobs; version,
arch, disk_free_bytes, disk_total_bytes on runners) — run
php artisan migrate --force as usual. Existing runners will start
reporting the new capability fields on their next heartbeat after being
restarted with the updated binary; until then those fields just show as
unset, nothing breaks.