fix(database): suggest closest supported type on schema typos

[divyasinghds]

A new user typing BIGINTEGER (mixing BIGINT with Python's int), BOLEAN (missing O), NUMRIC (missing E), etc. used to get a bare Unsupported MySQL type: <typo> error with no hint. They had to spelunk the schema docs or guess.

Fix

Levenshtein-based "Did you mean X?" hint in _get_sqlalchemy_type's ValueError. Threshold d ≤ 3 — close enough to catch realistic typos (BIGINTEGER, INTGER, NUMRIC, BOLEAN, VARCAHR), narrow enough that GEOMETRY (d=6 to nearest) gets no misleading hint.

The error also prints the full supported-type list, so cases where edit-distance-nearest ≠ intent-nearest (e.g. BIGINTEGER's nearest by edits is INTEGER, even though the user clearly wanted BIGINT) still get help — BIGINT is right there in the list.

Test plan

• BIGINTEGER → "Did you mean 'INTEGER'" + BIGINT in the supported list
• GEOMETRY → no "Did you mean" (stays Unsupported only)
• Parametrised: INTGER→INTEGER, NUMRIC→NUMERIC, BOLEAN→BOOLEAN, VARCAHR→VARCHAR

Surfaced by adversarial new-user testing N3 (parent #261).

🤖 Generated with Claude Code

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Note

Low Risk
Only changes error text for invalid schema types; valid type mapping and DDL behavior are unchanged.

Overview
Unsupported MySQL type strings in user schemas now get actionable ValueError messages instead of a bare "Unsupported" line.

_get_sqlalchemy_type calls a new _suggest_type helper (Levenshtein distance ≤ 3 against type_mapping keys). Close typos like BIGINTEGER, INTGER, or NUMRIC raise Did you mean '…'? plus a Supported types: list sorted from the mapping. Distant names such as GEOMETRY still fail without a misleading suggestion.

Tests cover the suggestion path, the no-suggestion path, and a parametrized set of common misspellings.

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[LukasWodka]

👋 Heads-up — Code review queue is at 15 / 8

Above the WIP limit. The team convention is to review existing PRs before opening new work.

Open PRs currently in Code review (oldest first):

• averaging-service#115 — Release: staging → main (averaging correctness sweep → production) · author: @aptracebloc · no reviewer assigned
• backend#798 — Release: develop → staging (12.06.2026) · author: @aptracebloc · no reviewer assigned
• client-runtime#105 — chore(ci): drop unused mysqlclient dep; report test coverage (Phase 0) · author: @LukasWodka · no reviewer assigned
• client-runtime#106 — fix(schema): sync vendored ingest.v1.json — restore token_classification · author: @LukasWodka · no reviewer assigned
• client-runtime#107 — fix(logging): retire obsolete logs_queue Service Bus path · author: @saadqbal · no reviewer assigned
• data-ingestors#253 — refactor(P3a): move per-category behavior flags into a ModalityRegistry · author: @LukasWodka · no reviewer assigned
• data-ingestors#255 — refactor(P3b): move validator factories into the ModalityRegistry · author: @LukasWodka · no reviewer assigned
• data-ingestors#256 — refactor(P3c): move sidecar-transfer factories into the ModalityRegistry · author: @LukasWodka · no reviewer assigned
• data-ingestors#257 — refactor(P3d): source data_format from the ModalityRegistry · author: @LukasWodka · no reviewer assigned
• data-ingestors#262 — fix(label): strip whitespace from label values to prevent silent class duplication (issue Whitespace-padded VARCHAR values are stored as distinct from the trimmed value (silent label-set corruption) #261) · author: @divyasinghds · no reviewer assigned

Pull from review before opening new work. (This is a nudge from the kanban WIP check, not a block.)