Feat 275 placeholder options

[mohammadsherif0]

Description

Type 8 prompt templates support optional per-token options, starting with Character limit on pdfText. Authors configure options in the template sidebar before insert; limits apply at resolution time (resolver and AI hook path), not on text written in the editor.

New User Features

• Optional Character limit on pdfText before insert (e.g. ~pdfText[1]{characterLimit:5000}~); omit for full retrieved text.
• Clearer type-8 placeholder descriptions, help tooltips, and preview examples.

New Dev Features

• placeholderOptions JSONB column on placeholder (seeded for type-8 pdfText with characterLimit).
• Shared placeholder-tokens module now supports options in token syntax: parse, format, validate, and pass them through when replacing tokens.
• When a prompt is resolved, each pdfText token is truncated only if that token has a valid characterLimit option; tokens without it keep the full retrieved text.

Improvements

• Removed global cap on stored ~pdfText~ base value so per-token limits control truncation.
• Type-8 sidebar validates token options; warns when an option row is incomplete but still inserts the placeholder.

Bug Fixes

• Template editor preview now updates correctly when placeholder examples load from the server.

Known Limitations

• Phase 1 per-token options apply to characterLimit on pdfText only. Other placeholders have no option support yet.
• editorText and submissionFiles still use the global 2000-character cap: unchanged in Phase 1; no per-token limit option for those yet.
• New option types or placeholders require a DB seed/migration plus resolver and sidebar wiring.

Future Steps

• Extend placeholderOptions and resolver handling to other placeholders and additional option types beyond character limit.

#275
#248