feat(go-config): multi-format codecs, envc CLI, fixtures, ASRs

- Module github.com/eslider/go-config with env/yaml/json/ini packages
- internal: source, keymap, merge, structconv, bytesutil
- cmd/envc: convert, get, merge
- docs/asr ASR-0001..0008, README/CHANGELOG/AGENTS refresh
- golangci-lint v2 config; tests + fixtures

Co-authored-by: Cursor <cursoragent@cursor.com>

fixtures/edge/deeply-nested.yaml

@@ -0,0 +1,5 @@
+a:
+  b:
+    c:
+      d:
+        e: leaf

fixtures/edge/key-styles.yaml

@@ -0,0 +1,4 @@
+topLevel: 1
+sub-Service: 2
+snake_case: 3
+CamelCase: 4

fixtures/edge/types.json

@@ -0,0 +1,7 @@
+{
+  "flag": true,
+  "count": 42,
+  "ratio": 3.14,
+  "nothing": null,
+  "nested": [1, 2]
+}

fixtures/identity/service.env

@@ -0,0 +1,7 @@
+SERVICE_NAME=my-service
+SERVICE_SUBSERVICE_NAME=abc
+SERVICE_SUBSERVICE_KEY=abs
+SERVICE_SUBSERVICE_TIMEOUT=30
+SERVICE_SUBSERVICE_ENABLED=true
+SERVICE_DATABASE_URL=postgres://localhost:5432/db
+SERVICE_DATABASE_POOLSIZE=10

fixtures/identity/service.ini

@@ -0,0 +1,12 @@
+[service]
+name = my-service
+
+[service.subservice]
+name = abc
+key = abs
+timeout = 30
+enabled = true
+
+[service.database]
+url = postgres://localhost:5432/db
+pool-size = 10

fixtures/identity/service.json

@@ -0,0 +1,15 @@
+{
+  "service": {
+    "name": "my-service",
+    "sub-service": {
+      "name": "abc",
+      "key": "abs",
+      "timeout": 30,
+      "enabled": true
+    },
+    "database": {
+      "url": "postgres://localhost:5432/db",
+      "pool-size": 10
+    }
+  }
+}

fixtures/identity/service.yaml

@@ -0,0 +1,10 @@
+service:
+  name: my-service
+  sub-service:
+    name: abc
+    key: abs
+    timeout: 30
+    enabled: true
+  database:
+    url: postgres://localhost:5432/db
+    pool-size: 10

fixtures/invalid/duplicate-keys.ini

@@ -0,0 +1,3 @@
+[sec]
+a = 1
+a = 2

fixtures/invalid/malformed.json

@@ -0,0 +1 @@
+{ not json

fixtures/invalid/malformed.yaml

@@ -0,0 +1 @@
+service: [unclosed

fixtures/merge/defaults.env

@@ -0,0 +1,7 @@
+SERVICE_NAME=default-name
+SERVICE_SUBSERVICE_NAME=default-sub
+SERVICE_SUBSERVICE_KEY=default-key
+SERVICE_SUBSERVICE_TIMEOUT=1
+SERVICE_SUBSERVICE_ENABLED=false
+SERVICE_DATABASE_URL=postgres://old
+SERVICE_DATABASE_POOLSIZE=1

fixtures/merge/defaults.yaml

@@ -0,0 +1,13 @@
+service:
+  name: default-name
+  sub-service:
+    name: default-sub
+    key: default-key
+    timeout: 1
+    enabled: false
+  hosts:
+    - a
+    - b
+  database:
+    url: postgres://old
+    pool-size: 1

fixtures/merge/expected-concat.yaml

@@ -0,0 +1,14 @@
+service:
+  name: default-name
+  sub-service:
+    name: overlay-name
+    key: default-key
+    timeout: 1
+    enabled: false
+  hosts:
+    - a
+    - b
+    - x
+  database:
+    url: postgres://old
+    pool-size: 1

fixtures/merge/expected-replace.yaml

@@ -0,0 +1,12 @@
+service:
+  name: default-name
+  sub-service:
+    name: overlay-name
+    key: default-key
+    timeout: 1
+    enabled: false
+  hosts:
+    - x
+  database:
+    url: postgres://old
+    pool-size: 1

fixtures/merge/overlay.env

@@ -0,0 +1 @@
+SERVICE_SUBSERVICE_NAME=overlay-name

fixtures/merge/overlay.yaml

@@ -0,0 +1,5 @@
+service:
+  sub-service:
+    name: overlay-name
+  hosts:
+    - x