refactor(firestore): modernize internal proto call sites and eliminate local declarations (#9076)

[quirogas]

Part 4 of stacked disentanglement (#8928). Transition @google-cloud/firestore to directly consume @google-cloud/firestore-api as its native Single Source of Truth for TypeScript declarations, removing static checked-in local proto types.

Background & Motivation

Historically, dev/protos/update.sh compiled static TypeScript interfaces (firestore_v1_proto_api.d.ts) using custom build transformations:

• Used --force-enum-string to convert protobuf numeric enums into string literal unions ('ASCENDING' | 'DESCENDING').
• Executed a Perl regex to replace 64-bit integer Long references with string.

While this simplified early static method signatures, it created dependency on static checked-in declaration files that risk drifting out of sync as upstream protobuf definitions evolve over time. Transitioning directly to @google-cloud/firestore-api provides continuous automated type generation without build script maintenance.

Summary of Changes

• Eliminate Static Local Types: Complete removal of dev/protos/firestore_v1_proto_api.d.ts, dev/protos/firestore_v1_proto_api.js, and dev/protos/v1.json, making @google-cloud/firestore-api our native Single Source of Truth.
• Bundle Protocol Isolation: Extract custom offline bundle persistence interfaces (bundle.proto), which belong strictly to the handwritten SDK wrapper and are independent of GAPIC models, into standalone local modules (dev/src/bundle-proto).
• Call-Site & Comparator Modernization: Update internal query dictionaries (directionOperators, comparisonOperators) and sorting algorithms to natively consume GAPIC enum objects and 64-bit Long structures.

Backward Compatibility Guarantee

• All internal sorting and query comparator algorithms implement dual matching (orderBy.direction === 'ASCENDING' || orderBy.direction === api.StructuredQuery.Direction.ASCENDING) to support both literal strings and numeric GAPIC enums interchangeably.
• Verified that during HTTP REST fallback execution (fallback: true), proto3-json-serializer inspects GAPIC reflection models and automatically translates numeric integer enum codes back into standard JSON string schema names before transmitting payloads over HTTP, guaranteeing zero regressions for REST consumers.

Internal: b/531788771

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📚 Stack Navigation Index

1. Layer 1 (Base Disentanglement & Runtime Forwarding): feat(firestore): decouple handwritten sdk wrapper from embedded gapic clients #8928
2. Layer 2 (Complete Decoupling & Dead Code Cleanup): feat(firestore)!: complete gapic decoupling, adopt subpath imports, and remove legacy proto code (#9074) #9074
3. Layer 3 (Automated Presubmit Bundle Size Guard): chore(firestore): add automated presubmit serverless bundle size regression guard (#9075) #9075
4. Layer 4 (Call-Site Modernization & Eliminate Local Protos): refactor(firestore): modernize internal proto call sites and eliminate local declarations (#9076) #9076

[gemini-code-assist]

Code Review

This pull request introduces a new TypeScript declaration file, bundle.d.ts, defining the custom Firestore bundle persistence protocol types. The review feedback focuses on improving type safety across these declarations. Specifically, it is recommended to replace several any types for time-related fields (createTime and readTime) with a dedicated Timestamp interface, define that Timestamp interface, and restrict the limitType field to the specific string union values 'FIRST' | 'LAST'.

[gemini-code-assist]

Using any for createTime reduces type safety. We should use a Timestamp interface instead.

Suggested change

	createTime?: any | null;
	createTime?: Timestamp | null;

[gemini-code-assist]

Using any for readTime reduces type safety. We should use a Timestamp interface instead.

Suggested change

	readTime?: any | null;
	readTime?: Timestamp | null;

[gemini-code-assist]

Using any for readTime reduces type safety. We should use a Timestamp interface instead.

Suggested change

	readTime?: any | null;
	readTime?: Timestamp | null;

[gemini-code-assist]

Define a Timestamp interface to represent protobuf Timestamps, and restrict limitType to the allowed string union values 'FIRST' | 'LAST' for better type safety.

  export interface BundledQuery {
    parent?: string | null;
    structuredQuery?: any | null;
    limitType?: 'FIRST' | 'LAST' | null;
  }
  export interface Timestamp {
    seconds?: string | number | null;
    nanos?: number | null;
  }