j139 dotenv: strip trailing inline comments and warn on non-token values

A `#` preceded by whitespace and outside quotes now ends the value, so
`TR_DEBUG_DRAW=0      # hides the grid` resolves to `0` instead of the
whole tail. Values that are still not plain tokens (whitespace, `#`, an
unclosed quote) get one `[dotenv] WARNING` line naming file, key, raw value
and the fact that the reader falls back to its DEFAULT, instead of being
applied silently. Guard test 29 -> 47 checks.

common_libs/tests/test_env_dotenv.nim

@@ -10,6 +10,8 @@
 ##   * resolution precedence (flag > TR_ENV_FILE > ./.env > .env next to the
 ##     executable > none);
 ##   * the FILE WINS over the real environment, and the conflict is reported;
+##   * a junky value (unrecognised) is WARNED ABOUT at load time instead of
+##     silently becoming the reader's default (j139);
 ##   * an explicitly requested missing file raises (the caller then exits
 ##     nonzero), while a missing DEFAULT file is a silent no-op.
 
@@ -166,12 +168,76 @@ proc testMissingFiles() =
   check "no file at all is a silent no-op",
         loadEnvFile(EnvFileChoice(path: "", source: "none", explicit: false)).len == 0
 
+# ── 5. inline comments (j139) and the junk-value warning ─────────────────────
+
+proc testInlineComments() =
+  let e = parseEnvFileContent(
+    "A=value  # comment\n" &
+    "B=\"a # b\"\n" &
+    "C='a # b'\n" &
+    "D=value#notacomment\n" &
+    "E=# comment\n" &
+    "# whole line\n" &
+    "F=0      # hides the heat grid\n" &
+    "G=both\n", "inline.env")
+  check "inline comment file yields 7 entries", e.len == 7
+  if e.len == 7:
+    check "`KEY=value  # comment` -> value", e[0].key == "A" and e[0].value == "value"
+    check "a `#` inside double quotes is DATA", e[1].value == "a # b"
+    check "a `#` inside single quotes is DATA", e[2].value == "a # b"
+    check "`KEY=value#notacomment` keeps the `#` (no whitespace before it)",
+          e[3].value == "value#notacomment"
+    check "`KEY=# comment` -> empty value (not an error)", e[4].value == ""
+    check "the reported bug shape `0      # comment` -> `0`", e[5].value == "0"
+    check "a line whose only content is a comment is still skipped", e[6].value == "both"
+
+  check "stripInlineComment is pure and exact",
+        stripInlineComment("x  # y").strip == "x" and
+        stripInlineComment("  # y").strip == "" and
+        stripInlineComment("\"a # b\"").strip == "\"a # b\""
+
+proc testJunkWarning() =
+  check "a plain token is never junky",
+        not looksJunky("0") and not looksJunky("off") and
+        not looksJunky("1.0,1.25") and
+        not looksJunky("/tmp/modularbot.log") and not looksJunky("")
+  check "whitespace / `#` / unbalanced quotes are junky",
+        looksJunky("0 # hides the grid") and looksJunky("a # b") and
+        looksJunky("\"unclosed")
+
+  # A junky value the inline-comment rule CANNOT fix: an unclosed quote, so
+  # the `#` is (correctly) treated as data and the whole tail stays in the value.
+  let f = writeTmp("junk.env", "TR_TEST_JUNK_J139=\"0    # hides the grid\n")
+  let conflicts = applyEnvFile(f)
+  check "a junky value is still APPLIED verbatim (the reader decides)",
+        conflicts.len == 0 and
+        getEnv("TR_TEST_JUNK_J139") == "\"0    # hides the grid"
+  delEnv("TR_TEST_JUNK_J139")
+
+  # the warning path itself: one line per offending key, naming file, key,
+  # raw value and what is used.
+  let w = junkWarnings(parseEnvFileContent(readFile(f), f), f)
+  check "a junky value produces exactly one warning",
+        w.len == 1
+  check "the warning names the file", w.len == 1 and f in w[0]
+  check "the warning names the key and the raw value",
+        w.len == 1 and "TR_TEST_JUNK_J139" in w[0] and "# hides the grid" in w[0]
+  check "the warning says what is used and how to fix it",
+        w.len == 1 and "DEFAULT" in w[0] and "its own line" in w[0]
+  check "a clean file produces no warning",
+        junkWarnings(parseEnvFileContent("A=0  # fine\nB=1.0,1.25\n", "c.env"),
+                     "c.env").len == 0
+  check "one line per key, no spam",
+        junkWarnings(parseEnvFileContent("A=x y\nB=p q\n", "d.env"), "d.env").len == 2
+
 # ── driver ───────────────────────────────────────────────────────────────────
 
 testParser()
 testResolution()
 testFileWins()
 testMissingFiles()
+testInlineComments()
+testJunkWarning()
 
 echo "\n", checks, " checks, ", failures, " failure(s)"
 if failures > 0: