feat(cli): add catalog-aware value completions

[BramVR]

Summary

• add catalog-aware completion for export datasets, sync/raw Data Types, raw targets/endpoints, scope keywords, Rollup modes, and source families
• preserve CSV prefixes, suppress duplicates, sort candidates lexically, and retain filesystem fallback only for path values
• derive candidates from typed registries with completion-policy and catalog drift guards

Proof

• Formatting: make fmt-check
• Lint: pinned golangci-lint v2.12.2, 0 issues
• Tests: go test ./...
• Race: go test -race ./...
• Build: make build
• Docs: make docs-check
• Project Site: make docs-site plus full Pages artifact smoke
• Built CLI: hidden callback candidates, CSV prefix/dedup, Rollup window=, path-only fallback, and deterministic generation
• Shells: Bash and Zsh generated scripts parse and load locally; Fish/PowerShell generation is deterministic, and hosted Windows exercises the PowerShell parser
• Security: go vet ./..., go mod verify, govulncheck (no vulnerabilities), TruffleHog/autoreview clean
• Public Model Identifier Gate: no model identifiers introduced
• Docs/changelog impact reviewed: install and generated completion docs updated; repository has no changelog file
• Public artifact confidentiality gate reviewed: no secrets, tokens, OAuth client JSON, personal Health Archive data, provider payloads, private paths, or identifying screenshots/logs are exposed

Notes

• Closes feat(cli): add catalog-aware value completions #401
• Dependency freshness: Cobra is current; modernc.org/sqlite has a direct v1.53.0 → v1.55.0 update, unrelated to this focused change and not vulnerability-driven
• Claude Opus review not required: all new discovery functions are under Go's internal package boundary; no public API contract changes
• Local Fish and PowerShell executables were unavailable; exact-head hosted Windows proof is required before merge

[Copilot]

Pull request overview

This PR adds catalog-aware, deterministic value completion to the CLI by introducing explicit “value completion policies” in the command/flag registry and wiring those into Cobra’s completion protocol. It sources candidates from typed catalogs (export datasets, Google Health Data Types/endpoints, rollup kinds, scope keywords, and source families), preserves CSV prefixes while deduplicating, and keeps filesystem completion enabled only for path values.

Changes:

• Add completion policy metadata to commandDef/flagSpec, validate registry coverage, and register per-flag/per-positional completion handlers.
• Introduce canonical catalog projection helpers for raw targets/endpoints, syncable/listable data types, and supported source families (with drift-guard tests).
• Update CLI help/docs to describe catalog-backed completions and path-only filesystem fallback.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
internal/googlehealth/scopes.go	Adds RawEndpointNames() catalog projection for raw endpoint completion.
internal/googlehealth/fetch.go	Introduces typed raw target kinds and exposes RawTargetNames() for completion.
internal/googlehealth/fetch_extra_test.go	Adds drift tests for raw endpoint/target completion projections.
internal/googlehealth/catalog.go	Adds completion views (SyncableDataTypes, ListableDataTypes, SupportedSourceFamilies) and source-family catalog mapping.
internal/googlehealth/catalog_test.go	Adds drift tests for completion view projections and copy safety.
cmd/gohealthcli/sync.go	Uses catalog-backed usage strings for rollup and source-family flags.
cmd/gohealthcli/connect_add_scopes.go	Exposes sorted scope keyword names for completion and keeps usage derived from canonical keyword set.
cmd/gohealthcli/completion.go	Implements policy-driven Cobra completion for flags/positionals, CSV prefix preservation, dedup, and sorting.
cmd/gohealthcli/completion_test.go	Adds protocol-level tests for catalog candidates, directives, stability, sorting, and path-only filesystem fallback.
cmd/gohealthcli/common_flags.go	Marks --config and --db as file-completable (filesystem fallback).
cmd/gohealthcli/commands.go	Adds completion policy fields and populates them across command registry surfaces.
docs/install.md	Documents catalog-backed completions and path-only filesystem fallback behavior.
docs/commands/completion.md	Updates completion command docs to reflect new value completion behavior and constraints.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.