test(atlas): add full Fortal portable parity

[leoafarias]

Summary

• replace the Button-only/20 rendered-only capture with one shared FortalAtlasEntry inventory for all 21 public Fortal components
• add real portable component/v2 adapters for basic compositions, controls, custom-painted/value controls, and compound components
• capture deterministic recipes, states, slots, anatomy, semantics, nested-component references, real Fortal style factories, and custom scalar bindings
• require strict generation with zero visible placeholders and one-to-one catalog recipe/state alignment
• package all portable documents and embedded component-scoped style libraries into the committed Fortal capture

Inventory

• 21 component documents
• 148 recipes
• 613 cells per theme
• 1,226 light/dark renders
• 111 bundle files including the manifest (110 indexed artifacts), 2,670,855 bytes
• zero rendered-only component fallbacks; atlas/fortal/styles is empty because styles are embedded per component

Dependency split

• Muse-owned mix_atlas and mix_atlas_capture packages are pinned to btwld/muse#6 at exact commit e258ee7655f2336b3abbeb783495f44fb9cf8730.
• Shared mix and mix_protocol tooling primitives are pinned to btwld/mix#984 at exact commit 691eae21bc4bb806a71387186a68cb1682db5474.
• Superseded Mix Atlas product PR btwld/mix#982 is no longer a dependency.

Verification

• fvm dart run melos run atlas:fortal
• fvm dart run melos run atlas:fortal:check
• fvm flutter test test/atlas/fortal_portable_parity_test.dart --reporter failures-only — 42 producer/portable theme matrices passed
• fvm dart run melos run ci — demo 97 passed; remix 1,796 passed
• Muse Atlas live GitHub validation at exact Remix head b2cf2efd3a975e53c6e7471b256053c44e153088: all 21 matrices, both themes, last-cell selection, Oracle, Inspect, Compare, and back navigation