PawMedia: contributor-owned image editing

[rita-aga]

Boundary

• adds optional temper.image_edit tooling for TemperPaw contributors
• keeps prompts byte-for-byte unchanged across the two allow-listed FAL edit models
• records immutable PawFS source/version and source/prompt/result hashes
• does not make Katagami a PawMedia caller or image-credit spender

Temper-native implementation

• MediaGenerationRequest.Edit action and state-visible provenance
• dedicated fal_image_edit WASM integration
• Cedar-scoped provider callbacks, HTTP, and secret access
• first-class fal_key vault configuration in Temper setup and dashboard
• ADR-004 records the ownership boundary

Verification

• fal-image-edit unit tests: 5 passed
• PawMedia integration contracts: 11 passed
• Monty REPL tests: 81 passed
• tool-catalog tests: 1 passed
• both PawMedia WASM modules build for wasm32
• live local source import and immutable FileVersion resolution
• missing-secret path fails visibly with fal_key is not configured
• GitHub CI passes

Draft pending explicit credential provisioning, real local provider E2E, proof report, deploy, Genesis publish, and installed-ref verification.