refactor: unify model source and weight lifecycle management

[leejet]

Summary

• Track model files, revisions and shard dependencies in ModelLoader, validating metadata before publishing updates.
• Centralize tensor source binding and invalidation in ModelManager, including shared LoRA management and prefixed LTX latent upsampler weights.
• Rebuild affected runner groups when sources change, invalidate merged PhotoMaker LoRA weights, and reject context reentry during refresh and execution.

Related Issue / Discussion

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Additional Information

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Checklist

• I have read and confirmed this PR follows the contribution guidelines.