feat: Add manifest-driven table UI

[djrarky]

Summary

Adds a generic plugin framework extension for rendering plugin-owned database tables from plugin.json declarations.

This lets plugins declare simple table management screens without adding plugin-specific Filament resources or hard-coded host logic. The host remains generic: m3u-editor reads schema.ui_tables, validates the declaration, and renders the table/form UI through reusable Filament components.

What changed

• Added schema.ui_tables support to plugin manifests.
• Added a generic plugin table page for create/edit/delete table records.
• Added PluginUiTableRegistry to centralise table lookup, ownership checks, prefill handling, JSON casts, and lookup options.
• Added PluginTableRecord as a lightweight dynamic Eloquent model for plugin-owned tables.
• Added table_select field support so plugin forms can select records from declared/plugin-owned tables.
• Added a Data tab on plugin edit pages linking to any declared table UIs.
• Extended manifest validation for declared table UIs and table_select fields.
• Added regression coverage for grouped plugin settings and declared table UIs.

Design notes

This intentionally avoids plugin-specific m3u-editor code. Plugins declare the shape of their admin tables in the manifest, and m3u-editor renders them using generic Filament table/form primitives.

Testing

• Pint passed for touched files.
• PHP syntax checks passed.
• Plugin validation passed.
• Focused test suite passed: 29 passed, 202 assertions.
• plugins:doctor reports healthy.
• plugins:discover finds canonical-channel-guardian [valid].