Add specifications for two-times upscale and unified depth plane features

- Introduced the two-times upscale specification detailing requirements for unified output, fixed model presets, arbitrary dimensions, and consistent job behavior.
- Added scenarios for existing models, repeated upscale, and handling of alpha preservation.
- Created the unified depth plane specification outlining geometry modes, stable interface, and asset evaluation.
- Defined scenarios for mode switching, relief and camera preservation, and validation of delivered assets.

openspec/specs/panorama-input-cropping/spec.md

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+# panorama-input-cropping Specification
+
+## Purpose
+TBD - created by archiving change auto-crop-panorama-input. Update Purpose after archive.
+## Requirements
+### Requirement: Panorama input uses an exact centered 2:1 crop
+The system SHALL prepare panorama conversion from the largest centered integer-pixel rectangle whose width is exactly twice its height. The prepared color material and AI analysis input MUST use the same cropped pixels without stretching, padding, or aspect-ratio resampling.
+
+#### Scenario: Source is wider than 2:1
+- **WHEN** a user converts a usable static image whose width is greater than twice its height
+- **THEN** the system crops columns equally where possible from the left and right and prepares an exact 2:1 input at the source height
+
+#### Scenario: Source is narrower than 2:1
+- **WHEN** a user converts a usable static image whose width is less than twice its height
+- **THEN** the system crops rows equally where possible from the top and bottom and prepares the largest exact 2:1 input at or below the source width
+
+#### Scenario: Source width is odd
+- **WHEN** a usable static source has an odd width that cannot be part of an exact integer-pixel 2:1 rectangle
+- **THEN** the system omits the unmatched column as part of its deterministic centered crop
+
+#### Scenario: Source is already 2:1
+- **WHEN** a user converts a usable static image whose width is exactly twice its height
+- **THEN** the system prepares the full source image without removing pixels
+
+### Requirement: Panorama crop is disclosed to the user
+The system SHALL issue one warning whenever panorama input preparation removes source pixels, and the warning MUST identify both the original and cropped pixel dimensions.
+
+#### Scenario: Conversion requires cropping
+- **WHEN** the computed 2:1 bounds differ from the source bounds
+- **THEN** the system reports a warning containing the source width and height and the cropped width and height
+
+#### Scenario: Conversion does not require cropping
+- **WHEN** the source bounds already form an exact 2:1 image
+- **THEN** the system does not report a crop warning
+
+### Requirement: Unsupported panorama sources remain rejected
+The system MUST reject animated images and images too small to produce a positive integer-pixel 2:1 crop before submitting panorama generation.
+
+#### Scenario: Source is animated
+- **WHEN** a user attempts to convert an animated image
+- **THEN** the system reports an error and does not submit panorama generation
+
+#### Scenario: Source cannot produce a positive crop
+- **WHEN** a source image cannot provide at least a 2-pixel-wide by 1-pixel-high crop
+- **THEN** the system reports an error and does not submit panorama generation
+