Feat/user data input

[Dinghye]

Summary

Adds a bring-your-own-data path: users with their own imagery (local patches, exported GeoTIFFs, training cubes) can compute embeddings directly, with no provider fetch and no GEE auth.

What's in here

• UserData declaration: register imagery once (pixels + collection + one band name per channel + optional spatial/temporal); the declaration, not the array shape, is the contract. bands may be omitted only for the canonical 12-band S2 L2A case; band identity is never guessed.
• Matching with refusal semantics: superset band sets are sliced and reordered into model band order automatically (shared provider band-alias vocabulary, e.g. NIR_NARROW → B8A); a collection mismatch or missing band raises ModelError naming what is missing; precomputed models always refuse. list_models_for_data reports the verdict for every catalog model without loading weights.
• Public API: get_embedding_from_data(model, data) / get_embeddings_batch_from_data(model, datas, batch_size=...); batch items carry their own spatial/temporal, dispatch grouped, results in input order. batch_size caps the per-forward batch for small GPUs.
• input_prep="tile" default for fairness: arrays larger than a model's input size are cut into model-native tiles at native resolution and stitched, so a 256px patch reaches clay as one pass and galileo as a 4×4 grid of 64px tiles instead of losing 15/16 of its pixels to a resize; "resize" opts out.
• Flexible-size models run natively: new EmbedderBase.resolve_input_image_size hook; olmoearth (FlexiViT) consumes any patch-divisible size as one seamless pass by default, warns above 512px (quadratic attention cost), and an explicit image_size restores fixed-size tiling.
• New embedder flags/hooks (no model-name branches): _requires_georef (clay/prithvi refuse spatial-less data — coordinates are never fabricated), resolve_input_image_size, olmoearth tiled_dispatch_model_config.
• Fix: clay's get_embeddings_batch_from_inputs no longer acquires a provider for prefetched inputs (it forced Earth Engine auth on GEE-less machines; single path already followed the lazy-provider convention).
• Docs: new docs/user_data.md (site-style admonitions, complete GeoTIFF-to-embedding and directory-to-feature-matrix examples), Input size column in the models overview, CHANGELOG entries.

Testing

test_user_data_matching.py + test_api_from_data.py (mock embedders, no weights/network; list_models_for_data also exercised against the real catalog), clay/olmoearth regression tests, contract tests updated deliberately (tiled_dispatch registry now pins {thor, olmoearth}); affected suites incl. test_export_input_prep_consistency.py pass, ruff clean.