chore: complete the shigola rebrand (MAPCO-11504)

[NivGreenstein]

Removes the last stale tegola references from code, comments, config, tests and workflows. The deliberate exceptions stay. Jira: MAPCO-11504. Docs PR: MapColonies/shigola-docs#18.

Base is development, because feature branches are cut from it and target it.

What changed and why

Two changes alter behaviour. Both were bugs the rename had papered over.

• Provider metrics are now shigola_*. atlas.SetObservability passed a literal "tegola" to Map.Collectors, so the PostGIS pool and query metrics were the one family still published as tegola_*. README's breaking-changes table already says "nothing emits the old names"; this makes that true. Any dashboard or alert on tegola_postgres_* or tegola_*provider_sql_query_seconds needs updating. The Grafana dashboard's provider_prefix workaround is removed. Pinned by TestProviderCollectorsArePrefixed.
• SHIGOLA_SQL_DEBUG now works. The docs document it, but debug.go read TEGOLA_SQL_DEBUG directly with os.Getenv, so the documented name did nothing. It now goes through the env.Getenv shim, so the legacy name still works and warns. Pinned by TestSQLDebugFlags.

The rest is a rename:

• Comments, CLI help, log messages and metric help text.
• Test fixtures, including the tracked cache/file/testfiles/tegola-cache directory. Test hostnames go to example.com rather than a made-up shigola domain.
• serve --help no longer advertises the removed /maps/... route.
• Comments that called the removed native routes "tegola's" now say they were removed.
• Comments about Tegola's own history (for example, "the grid tegola always served") now name Tegola, rather than attributing that history to Shigola.
• The CITE harness no longer accepts TEGOLA_PORT. It is a CI script, not a deployment setting.
• The fixture migration no longer drops a pre-rename tegola database. MAPCO-11479 retired that name.

Deliberately kept

• LICENSE.md, NOTICE.md, CHANGELOG.md, tms/LICENSE-morecantile, and the provenance sections of README and CONTRIBUTING. These are the licence obligation.
• Links to upstream issues and PRs (postgis.go, server.go, seed_purge_generator_test.go).
• The env shim's TEGOLA_ legacy prefix. It still accepts the old names and still warns.
• AWS_TEST_BUCKET: tegola-ci. It is an existing S3 bucket, which cannot be renamed. A comment in the workflow now records it as the remaining exception.
• internal/build/stamp_path_test.go names github.com/go-spatial/tegola/... on purpose. It is the input for the "path still naming upstream" case.

Verification

• Full suite with RUN_POSTGIS_TESTS=yes against the fixture DB, under both -race and CGO_ENABLED=0, on arm64. The only failures were three pre-existing ones that also fail on unmodified development:
  • TestValidateTileInGrid and TestTile/a_matrix_the_scheme_does_not_have fail on arm64 only.
  • TestTracedRequestPublishesNoNewMetrics is a known flake.
• The affected packages, run under amd64 (CI's architecture): all pass. go vet is clean, and the gofmt -s gate is clean.
• Attribution check after the bulk edit:
  • The attribution files are unchanged against development.
  • Every go-spatial reference survives, except the six in internal/env test data, which are URL-parsing fixtures and not attribution.
  • git grep -iE 'shigola\.io|go-spatial/shigola|go-spatial\.org/shigola|MapColonies/tegola' returns nothing.

Not done here

• The redis, S3 and azblob gated tests were not run locally.
• The prometheus observer still hard-codes its own shigola_* prefixes, separately from the new atlas.metricPrefix. Sharing one constant would be a small follow-up, but it is outside the scope of a rename.

🤖 Generated with Claude Code

[coveralls]

Coverage Report for CI Build 7

Coverage increased (+0.09%) to 56.828%

Details

• Coverage increased (+0.09%) from the base build.
• Patch coverage: 12 uncovered changes across 4 files (13 of 25 lines covered, 52.0%).
• No coverage regressions found.

Uncovered Changes

File	Changed	Covered	%
observability/prometheus/cache.go	8	0	0.0%
observability/prometheus/prometheus.go	2	0	0.0%
cmd/shigola_lambda/main.go	1	0	0.0%
observability/prometheus/build_info.go	1	0	0.0%
Total (10 files)	25	13	52.0%

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	10611
Covered Lines:	6030
Line Coverage:	56.83%
Coverage Strength:	121.31 hits per line

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💛 - Coveralls