twbparser 0.4.0

New features

twb_sheet_shelves() — extract every field placed on rows, cols, or an encoding shelf (color, size, label, detail, tooltip) for one or all worksheets.
twb_sheet_filters() — extract worksheet-level filters including categorical member lists, range min/max, and include/exclude mode.
twb_sheet_axes() — extract per-axis configuration: reversed, include-zero, and scale type (linear, log, …).
twb_sheet_sorts() — extract sort directives with sort direction and method (field aggregate, alphabetic, manual, data-source order).
All four are exposed on TwbParser as get_sheet_shelves(), get_sheet_filters(), get_sheet_axes(), get_sheet_sorts() and as no-parens active bindings (parser$sheet_shelves, etc.).

twb_dashboard_sheets() — list every worksheet placed on a dashboard with zone id and pixel position (x, y, w, h).
twb_dashboard_layout() — full zone tree including parent zone id, component type (worksheet / filter / container / …), layout type (tiled / floating), and pixel bounds.
twb_dashboard_actions() — extract filter and URL actions with source and target sheets, run-on trigger type, and URL value.
All three are exposed on TwbParser as get_dashboard_sheets(), get_dashboard_layout(), get_dashboard_actions() and as active bindings.

plot_relationship_graph(): fixed edge direction — the from vertex was incorrectly built from right_field instead of left_field.
plot_source_join_graph(): fixed reference to non-existent columns left_source / right_source; replaced with left_table / right_table.
infer_implicit_relationships(): added deduplication before the field-name self-join to prevent Cartesian explosion when many tables share a field name; added relationship = "many-to-many" to suppress the dplyr 1.1+ warning.
Fixed integer_ typo in insights.R that caused errors when parsing dashboard zone dimensions.

Canonical .twb_clean_table() and .twb_clean_field() helpers added to utils.R, replacing four independent copies scattered across fields.R, calculated_fields.R, relationships.R, joins.R, and dependency_graph.R.
.twb_clean_field() now correctly strips Tableau column-instance prefixes (none:Category:nk → Category) and returns unnamed vectors.

Remove use of unlockBinding() in internal TwbParser active-binding helpers. This avoids CRAN’s “possibly unsafe call” NOTE while keeping the same user-facing behaviour for no-parens properties (overview, pages, datasources, etc.).