Implement Tf, Td, TD, Tm, T* operators for Phase 3.1 text state.
- Add TSTAR_ZERO_LEADING, FONT_RESOURCE_NOT_FOUND, FONT_SIZE_ZERO_OR_NEGATIVE diagnostics
- Add move_text, move_text_set_leading, set_text_matrix, next_line, set_font methods to GraphicsState
- Refactor execute_with_do to use gstate.text_matrix instead of local TextMatrix
- Implement Tf with ResourceStack font resolution and size clamping
- Implement Td/TD/Tm/T* operators with correct matrix semantics
- Add acceptance criteria tests for all operators
Per PDF spec:
- Td: text_line_matrix = translate(tx, ty) * text_line_matrix
- TD: same as Td, plus sets leading = -ty
- Tm: overwrites both text_matrix and text_line_matrix (does not accumulate)
- T*: equivalent to Td 0 -leading
- Tf: resolves font name from ResourceStack, clamps size <= 0 to 1.0
Closes: pdftract-4x0y
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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