refactor: replace array-based expressions with typed class hierarchy

Replace the old Lisp-like array expression representation
(["AND", ["PARAM", ...], ...]) with a class hierarchy rooted in
an abstract Expression class (Literal, Parameter, Binary, Unary,
FunctionCall, Conditional). This gives compile-time type safety
to expression construction, evaluation, and pattern matching.

Key changes:
- New lib/common/expression.ts defines the class hierarchy with
  map/evaluate/toString methods
- Rewrite parser as hand-rolled recursive descent, removing the
  parsimmon dependency
- Extend Path with a colon separator to unify parameter identity
  and attributes into a single address space (e.g.
  "Device.WiFi.SSID.1.Name:writable"). The colon field tracks
  how many trailing segments are attribute qualifiers. PathSet
  rewritten with separate param/attr segment indexes
- Flatten device attribute representation in the UI to
  colon-delimited keys mirroring the new path syntax

npm-shrinkwrap.json

@@ -22,7 +22,6 @@
         "koa-jwt": "^4.0.3",
         "koa-send": "^5.0.1",
         "mongodb": "^4.16.0",
-        "parsimmon": "^1.18.1",
         "seedrandom": "^3.0.5"
       },
       "bin": {
@@ -46,7 +45,6 @@
         "@types/koa-compress": "^4.0.7",
         "@types/mithril": "^2.2.7",
         "@types/node": "^25.3.5",
-        "@types/parsimmon": "^1.10.9",
         "@types/seedrandom": "^3.0.8",
         "esbuild": "^0.27.4",
         "eslint": "^10.0.3",
@@ -3028,12 +3026,6 @@
         "undici-types": "~7.18.0"
       }
     },
-    "node_modules/@types/parsimmon": {
-      "version": "1.10.9",
-      "resolved": "https://registry.npmjs.org/@types/parsimmon/-/parsimmon-1.10.9.tgz",
-      "integrity": "sha512-O2M2x1w+m7gWLen8i5DOy6tWRnbRcsW6Pke3j3HAsJUrPb4g0MgjksIUm2aqUtCYxy7Qjr3CzjjwQBzhiGn46A==",
-      "dev": true
-    },
     "node_modules/@types/qs": {
       "version": "6.15.0",
       "resolved": "https://registry.npmjs.org/@types/qs/-/qs-6.15.0.tgz",
@@ -5323,11 +5315,6 @@
         "node": ">= 0.8"
       }
     },
-    "node_modules/parsimmon": {
-      "version": "1.18.1",
-      "resolved": "https://registry.npmjs.org/parsimmon/-/parsimmon-1.18.1.tgz",
-      "integrity": "sha512-u7p959wLfGAhJpSDJVYXoyMCXWYwHia78HhRBWqk7AIbxdmlrfdp5wX0l3xv/iTSH5HvhN9K7o26hwwpgS5Nmw=="
-    },
     "node_modules/path-exists": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/path-exists/-/path-exists-4.0.0.tgz",
@@ -8317,12 +8304,6 @@
         "undici-types": "~7.18.0"
       }
     },
-    "@types/parsimmon": {
-      "version": "1.10.9",
-      "resolved": "https://registry.npmjs.org/@types/parsimmon/-/parsimmon-1.10.9.tgz",
-      "integrity": "sha512-O2M2x1w+m7gWLen8i5DOy6tWRnbRcsW6Pke3j3HAsJUrPb4g0MgjksIUm2aqUtCYxy7Qjr3CzjjwQBzhiGn46A==",
-      "dev": true
-    },
     "@types/qs": {
       "version": "6.15.0",
       "resolved": "https://registry.npmjs.org/@types/qs/-/qs-6.15.0.tgz",
@@ -9871,11 +9852,6 @@
       "resolved": "https://registry.npmjs.org/parseurl/-/parseurl-1.3.3.tgz",
       "integrity": "sha512-CiyeOxFT/JZyN5m0z9PfXw4SCBJ6Sygz1Dpl0wqjlhDEGGBP1GnsUVEL0p63hoG1fcj3fHynXi9NYO4nWOL+qQ=="
     },
-    "parsimmon": {
-      "version": "1.18.1",
-      "resolved": "https://registry.npmjs.org/parsimmon/-/parsimmon-1.18.1.tgz",
-      "integrity": "sha512-u7p959wLfGAhJpSDJVYXoyMCXWYwHia78HhRBWqk7AIbxdmlrfdp5wX0l3xv/iTSH5HvhN9K7o26hwwpgS5Nmw=="
-    },
     "path-exists": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/path-exists/-/path-exists-4.0.0.tgz",