add epm — El Package Manager

Introduces epm/, a new component written entirely in native El.
epm manages vessels (El's deployable package format): publish to Engram,
install with full dependency resolution, list registry contents, and
inspect vessel metadata.

- epm/manifest.el         — package manifest
- epm/src/manifest.el     — vessel/package manifest parser (line-by-line,
                            same approach as elb.el)
- epm/src/registry.el     — Engram-backed vessel registry (POST /api/nodes,
                            GET /api/search); vessels stored as Entity nodes
                            with label "vessel:<name>:<version>"
- epm/src/install.el      — topological dependency resolver with cycle
                            detection; installs to .epm/vessels/<name>/
- epm/src/epm.el          — main entry point: publish / install / list / info

epm/src/manifest.el

@@ -0,0 +1,175 @@
+// epm/src/manifest.el — vessel and package manifest parser
+//
+// Parses manifest.el files in the vessel/package format:
+//
+//   vessel "el-auth" {
+//       version "0.1.0"
+//       description "..."
+//       authors ["..."]
+//       edition "2026"
+//   }
+//
+//   dependencies {
+//       el-platform "1.0"
+//       el-identity "0.1"
+//   }
+//
+//   build {
+//       entry "src/main.el"
+//       output "dist/"
+//   }
+//
+// Parsing is line-by-line string extraction, same approach as elb.el.
+// No AST, no grammar — sufficient for well-formed manifests.
+
+// ── String extraction helpers ─────────────────────────────────────────────────
+
+// extract_quoted extracts the first double-quoted token from a string.
+// Returns "" if no quoted token is found.
+// Example: extract_quoted("vessel \"el-auth\" {") -> "el-auth"
+fn extract_quoted(s: String) -> String {
+    let first: Int = str_index_of(s, "\"")
+    if first < 0 { return "" }
+    let after: String = str_slice(s, first + 1, str_len(s))
+    let close: Int = str_index_of(after, "\"")
+    if close < 0 { return "" }
+    return str_slice(after, 0, close)
+}
+
+// ── Manifest field extraction ─────────────────────────────────────────────────
+
+// manifest_name extracts the vessel or package name from manifest source.
+// Recognises both "vessel" and "package" block headers.
+fn manifest_name(src: String) -> String {
+    let lines: [String] = str_split(src, "\n")
+    let n: Int = native_list_len(lines)
+    let i: Int = 0
+    while i < n {
+        let line: String = native_list_get(lines, i)
+        let t: String = str_trim(line)
+        if str_starts_with(t, "vessel ") {
+            return extract_quoted(t)
+        }
+        if str_starts_with(t, "package ") {
+            return extract_quoted(t)
+        }
+        let i = i + 1
+    }
+    return ""
+}
+
+// manifest_version extracts the version string from manifest source.
+fn manifest_version(src: String) -> String {
+    let lines: [String] = str_split(src, "\n")
+    let n: Int = native_list_len(lines)
+    let i: Int = 0
+    while i < n {
+        let line: String = native_list_get(lines, i)
+        let t: String = str_trim(line)
+        if str_starts_with(t, "version ") {
+            return extract_quoted(t)
+        }
+        let i = i + 1
+    }
+    return ""
+}
+
+// manifest_description extracts the description string from manifest source.
+fn manifest_description(src: String) -> String {
+    let lines: [String] = str_split(src, "\n")
+    let n: Int = native_list_len(lines)
+    let i: Int = 0
+    while i < n {
+        let line: String = native_list_get(lines, i)
+        let t: String = str_trim(line)
+        if str_starts_with(t, "description ") {
+            return extract_quoted(t)
+        }
+        let i = i + 1
+    }
+    return ""
+}
+
+// manifest_entry extracts the build entry file from manifest source.
+fn manifest_entry(src: String) -> String {
+    let lines: [String] = str_split(src, "\n")
+    let n: Int = native_list_len(lines)
+    let i: Int = 0
+    while i < n {
+        let line: String = native_list_get(lines, i)
+        let t: String = str_trim(line)
+        if str_starts_with(t, "entry ") {
+            return extract_quoted(t)
+        }
+        let i = i + 1
+    }
+    return ""
+}
+
+// manifest_deps extracts dependencies as a JSON array of {"name":..., "version":...} objects.
+//
+// Scans lines inside the dependencies { ... } block.
+// Each dep line looks like:
+//   el-platform "1.0"
+//
+// Returns a JSON array string, e.g.:
+//   [{"name":"el-platform","version":"1.0"},{"name":"el-identity","version":"0.1"}]
+fn manifest_deps(src: String) -> String {
+    let lines: [String] = str_split(src, "\n")
+    let n: Int = native_list_len(lines)
+    let in_deps: Bool = false
+    let result: String = "["
+    let count: Int = 0
+    let i: Int = 0
+    while i < n {
+        let line: String = native_list_get(lines, i)
+        let t: String = str_trim(line)
+
+        // Detect entry into dependencies block
+        if str_eq(t, "dependencies {") {
+            let in_deps = true
+            let i = i + 1
+        } else {
+            if in_deps {
+                // Detect exit from block
+                if str_eq(t, "}") {
+                    let in_deps = false
+                } else {
+                    // Each dep line: name "version"
+                    // Find first space to split name from quoted version
+                    let sp: Int = str_index_of(t, " ")
+                    if sp > 0 {
+                        let dep_name: String = str_slice(t, 0, sp)
+                        let rest: String = str_trim(str_slice(t, sp, str_len(t)))
+                        let dep_ver: String = extract_quoted(rest)
+                        if !str_eq(dep_name, "") {
+                            let entry: String = "{\"name\":\"" + dep_name + "\",\"version\":\"" + dep_ver + "\"}"
+                            if count == 0 {
+                                let result = result + entry
+                            } else {
+                                let result = result + "," + entry
+                            }
+                            let count = count + 1
+                        }
+                    }
+                }
+            }
+            let i = i + 1
+        }
+    }
+    return result + "]"
+}
+
+// manifest_is_vessel returns true if the manifest declares a vessel (not a package).
+fn manifest_is_vessel(src: String) -> Bool {
+    let lines: [String] = str_split(src, "\n")
+    let n: Int = native_list_len(lines)
+    let i: Int = 0
+    while i < n {
+        let line: String = native_list_get(lines, i)
+        let t: String = str_trim(line)
+        if str_starts_with(t, "vessel ") { return true }
+        let i = i + 1
+    }
+    return false
+}