feat: autosuggest for Link fields on data table records

[esafwan]

Summary

• Replaces the bare text <Input> previously used for Link fieldtype columns with a proper LinkFieldInput component: async, debounced search against the target Huf Data Table's rows, results shown in a searchable dropdown (reusing the existing Combobox primitive already used in TriggerFieldsRenderer.tsx), selecting a row sets the actual link value.
• Link targets are already restricted server-side to other Huf Data Tables only (pre-existing validation in validators.py) — no backend change needed for that part.
• Extends the shared Combobox with two new optional, backward-compatible props (onSearchChange, shouldFilter) so other future async-search dropdowns can reuse it too.

Bugs found and fixed during live verification (not just static checks)

• First implementation called get_table_schema(field.options), but field.options holds the target's doctype_name while get_table_schema expects the Huf Data Table registry record's own name — these are different identifiers and the call failed with "not found". Fixed by resolving the registry record directly via db.getDocList('Huf Data Table', { filters: [['doctype_name', '=', targetDoctype]] }).
• Confirmed end-to-end on the live bench: typing in the dropdown returns matching rows, selecting one sets the link value correctly, shown in screenshots below.

Screenshots (live bench)

Autosuggest dropdown while typing:

After selecting a row:

Test plan

• yarn typecheck — 0 errors
• yarn lint — 0 errors (60 pre-existing unrelated warnings)
• Verified live on bench: created a temporary test table with a Link field to Customers, confirmed search-as-you-type and selection work end-to-end (test table removed after verification)

[esafwan]

Superseded by consolidated Data Tables PR #460, now included in integration PR #468.