fix(zone): prevent data source .zone_id from being mangled to .name_id

[koslib]

Problem

When tf-migrate migrate processes configs that reference the zone data source's zone_id output (e.g. in import blocks or string interpolations), the migration produces an invalid reference:

# Input (v4)
id = "${data.cloudflare_zone.this.zone_id}/security_header"

# Buggy output
id = "${data.cloudflare_zone.this.name_id}/security_header"
# → Error: This object has no argument, nested block, or exported attribute named "name_id".

The correct v5 output is .id:

id = "${data.cloudflare_zone.this.id}/security_header"

Root cause

Two compounding issues introduced in #295:

1. The regex built in applyGlobalPostprocessing for computed-attribute mappings had no trailing word boundary. The cloudflare_zone resource rule (\.zone → .name) matched the prefix of .zone_id, silently rewriting it to .name_id.

2. Because cloudflare_zone is an unanchored substring of data.cloudflare_zone, the resource rule also leaked onto data source references. The data.cloudflare_zone migrator had no mapping of its own to correctly handle its zone_id output attribute.

Fix

cmd/tf-migrate/main.go — add regexp.QuoteMeta and a trailing \b word boundary to both the computed-attribute-mapping and attribute-rename regex builders in applyGlobalPostprocessing. This prevents any attribute name from being matched as a prefix of a longer one, and ensures resource-type strings containing . are treated as literals.

internal/datasources/zone/v4_to_v5.go — add GetComputedAttributeMappings() to the data source migrator so cross-file zone_id output references are explicitly rewritten to id.

Tests

• TestComputedAttrMappingBoundary (unit) — verifies the boundary fix: .zone_id is not touched by the resource rule, .zone_id is correctly rewritten to .id by the datasource rule, and valid .name references are preserved.
• Scenario 8 in the zone_datasource integration fixture — covers an import block and output using .zone_id, asserting the output is .id.

Test layers run: make test (unit + integration) — all pass.

Related

Regression from #295.