feat: normalize auto model names and algorithm virtual slugs through entrypoints

Summary

Normalize the existing auto_model_name, auto_model_names, and algorithm virtual slugs into the new entrypoints/recipes model so compatibility behavior is explicit instead of scattered across request handling.

Parent roadmap: #2287 Parent issue: #2331 Related code: src/semantic-router/pkg/config/config.go, src/semantic-router/pkg/extproc, src/vllm-sr/cli, deploy/recipes, src/semantic-router/pkg/dsl

Motivation

Multiple recipe support should not leave old auto-model aliases and algorithm virtual slugs as special cases. The current config has AutoModelName and AutoModelNames, while Looper/MoM-style virtual names have historically acted like model names. These should map into entrypoints outside routing, then select a named recipe/profile.

Scope

Define compatibility and normalization for:

• auto_model_name and auto_model_names migration into entrypoints;
• algorithm virtual slugs such as MoM/Looper/Fusion-style request model names;
• default working recipe mapping for vllm-sr/auto, auto, and existing aliases;
• config dump/validate output that explains normalized entrypoints;
• CLI/dashboard/operator handling of compatibility fields.

Non-goals

• Do not remove legacy fields without migration and validation errors.
• Do not put entrypoints inside routing; entrypoints select a recipe from above routing.
• Do not couple algorithm slugs to signal definitions.

Acceptance criteria

• Existing auto model names continue to route through a normalized entrypoint representation.
• Multiple recipe configs can map different virtual model names to different recipes.
• Config validation detects ambiguous aliases and conflicting entrypoint mappings.
• Docs explain migration from old auto-model fields.