chore(scripts): delete one-shot scripts, the fix_tool crate, and unused workspace deps

[cunninghamcard-bit]

Closes #168. Track A, item A1 of #166.

Every file under scripts/ was audited for references (CI, docs, other scripts, source comments), for inputs that still exist, and for whether it can run at all. The issue carries the per-script evidence; the short version:

Deleted (16 scripts, one crate, four workspace deps; −2,117 lines)

• fix_profiles{,2..5}.rs: target a fix-profiles package that does not exist; their edit is already in the tree.
• check_missing.py, list_wrong_providers.py, revert_wrong_inventory.py, update_inventory_status.py: flipped cells in rfc/0004 during the provider-generation session.
• migrate_openai_compatible_{test,standalone}.py: removed Shell types that are already gone.
• gen_provider_registry.py: reads openai_compat_registry.rs, which no longer exists.
• gen_responses_convert.py: refuses to run by its own docstring; responses_convert.rs is hand-maintained.
• generate_all_providers.py, update_lib_rs.py, gen_vertex_maas_providers.py: scaffolded the pre-phase-4 thin-wrapper .rs files once. Since the registry landed (28fe708) providers are added as rows in provider_registry.json (e.g. InferenceHub, feat: add InferenceHub provider to OpenAI-compatible registry #22), the outputs carry no generated marker and have been hand-edited, so re-running would overwrite them. Restorable from history if ever needed.
• scripts/fix_tool: a Hello, world! workspace member compiled on every build.
• schemars, proc-macro2, syn, quote: workspace dependencies with no consumer.

Kept: generate_thin_wrapper_cassettes.py (cassette provenance cited by conformance_test.rs; retires with B2), the two cassette converters, the two LiteLLM survey scripts, responses_similarity_audit.py (retires with B6), and all live tooling.

Also: provider.rs no longer points at the deleted generator; root .gitignore covers __pycache__/ everywhere.

Note: RFC-0033 (which records this audit in its A1 row) is not part of this diff; it lands with #176, which also ships the unified sync tool that replaces the two LiteLLM scanners kept here.

Verification: cargo check -p aimux-providers, cargo fmt --check; nothing in CI referenced a deleted file.

[cunninghamcard-bit]

Withdrawn for now: the scope (which scripts to delete versus keep) is still under discussion in #168. Branch kept; will reopen or replace once settled.

[cunninghamcard-bit]

Reopened after settling the scope in #168: the deletion list is unchanged; the replacement for the removed generators is the registry maintenance flow (weekly models.dev diff report + monthly reachability probe, generator rule: do-not-edit header + CI --check) tracked in the follow-up issues linked from #168.