revert: remove download size estimates

docs/EXTENSION_DEVELOPMENT.md

@@ -148,53 +148,6 @@ labels, with `downloadFallbackTier` helping classify `best` and `default`;
 explicit kinds avoid ambiguity for custom IDs. Descriptions are not used
 because they may describe other fallback formats.
 
-### Estimated download sizes
-
-The quality picker estimates audio size locally from the known track durations.
-An optional `sizeEstimate` object on a quality option supplies audio parameters
-for custom IDs without resolving streams or triggering verification:
-
-```json
-{
-  "id": "studio",
-  "label": "Best FLAC",
-  "kind": "lossless",
-  "sizeEstimate": {
-    "bitDepth": 24,
-    "sampleRate": 192000,
-    "channels": 2,
-    "isMaximum": true
-  }
-}
-```
-
-- For encoded audio, supply `bitrateKbps` (total target bitrate across channels).
-  For example, `"sizeEstimate": {"bitrateKbps": 256}`.
-- For compressed lossless audio, supply `bitDepth` and `sampleRate` in Hz.
-  `channels` defaults to 2. Do not use this model for uncompressed PCM.
-- Set `isMaximum: true` for a lossless tier that can return lower quality.
-  The picker caps the declared depth/rate using each track's `audio_quality`
-  (for example, `16bit/44.1kHz` or `24bit/96kHz`). Metadata must belong to the
-  selected provider; missing or incomplete quality stays unavailable.
-  A capped bitrate alone remains unavailable.
-- Omitted parameters remain unknown. Older extensions retain estimates for
-  the picker's legacy `LOSSLESS`, `HI_RES`, and `HI_RES_LOSSLESS` tiers and
-  explicit codec/bitrate IDs or labels such as `opus_256` or `Opus 256kbps`.
-  `best`, `default`, and `flac` options with `kind: "lossless"` can use track
-  quality directly. Other generic and spatial tiers need explicit parameters.
-
-Lossy estimates use duration × bitrate / 8. Lossless estimates use a rough
-65% of uncompressed PCM size at the effective track quality. This is a comparison
-heuristic, not measured compression for the recording or a guaranteed size.
-Do not combine a CD-quality minimum with a hi-res maximum: that range hides
-the distinction between tiers and provides little useful size information.
-Estimates exclude artwork, tags, and container overhead. They describe the
-selected quality before automatic conversion, with a separate converted-size
-estimate when enabled. Fallback quality and intermediate transfers can change
-both the final size and data usage. Collection estimates sum each track's
-individual estimate. If any selected track lacks the required metadata,
-the picker does not show a partial sum as a complete total.
-
 ### Permissions
 
 ```json