ArcGIS metadata: full plain-text descriptions, data dates, source block — fork-first for upstream #84

[sgarcese]

Fork-side tracking for thealphacubicle#84. Removes the 300-character cut (the HUD FMR description is 3,539 characters), shows editingInfo dates, and adds a citation footer.

[sgarcese]

Done in #38. get_dataset shows the full description as plain text (FMR: 3,538 characters of HTML become 1,967 characters of text, nothing cut) plus the layer's data and schema edit dates (FMR data: 2025-09-30). get_schema adds string lengths and domains, and query_data/aggregate_data end with a source block. Metadata XML field labels are left for a follow-up. Upstream: thealphacubicle#84.